Changes to mtools

mplotqueries: included a new plot type 'connchurn' that shows opened vs. closed connections over time (#77, #74).
mplotqueries: removed redundant --type duration plot and set the default to --type scatter --yaxis duration.
mloginfo: new tool that summarizes log file information, including start/end time, version if present, and optionally restarts.
added nosetests infrastructure and first tests for mlaunch and mlogfilter (#39).
added internal LogFile class that offers helper methods around log files (#80).
fixed bug where mlogfilter --shorten was off by one character.

mlogvis: fixed a bug displaying the data in the wrong time zone (#70).
mplotqueries: fixed bug where a plot's argument sub-parser (e.g. for --bucketsize) couldn't deal with stdin.
mplotqueries: fixed bug that caused crash when there was no data to plot (#68).
mlogfilter: fixed bug that prevented --from and --to to be used with stdin (#73).
fixed bug parsing durations of log lines that have a float instead of int value (like 123.45ms).
implemented ISO-8601 timestamp format parsing for upcoming change in MongoDB 2.6 (#76).

mplotqueries: new plot types: "scatter" can plot various counters on the y-axis, "nscanned/n" plots inefficient queries (#58).
mplotqueries: added footnote ("created with mtools") including version. Can be toggled on/off with 'f' (#33).
mplotqueries: added histogram plots (--type histogram) with variable bucket size (#25).
mplotqueries: always plot full range of logfile on x-axis, even if data points start later or end earlier (#60).
mlogfilter: added human-readable option (--human) that inserts , in large numbers and calculates durations in hrs,min,sec. (#8).
mlogdistinct: improved log2code matching and cleaned up log2code match database.

mlogvis: doesn't require webserver anymore. Data is directly stored in self-contained html file (#57).
mlogvis: when clicking reset, keep group selection, only reset zoom window (#56).
mlaunch: different directory name will no longer create a nested data folder (#54).
mlaunch: arguments unknown to mlaunch are checked against mongod and mongos and only passed on if they are accepted (#55).
mlaunch: now you can specify a path for the mongod and mongos binaries with --binarypath PATH (#46).
mlaunch: positional argument for directory name removed. directory name now requires --dir. default is ./data.

fixed timezone bug in mlogmerge (#24)
allow for multiple mongos in mlaunch with --mongos NUM parameter (#30)
mlaunch can now take any additional single arguments (like -vvv or --notablescan) and pass it on to the mongod/s instances (#31)
all scripts now have --version flag (inherited from BaseCmdLineTool) (#34)
added --fast option to mlogfilter (#37)
mlogvis title added and legend height determined automatically (#45)
mlaunch now checks if port is available before trying to start and exits if port is already in use (#43)
improved mlogfilter --from / --to parsing, now supports sole relative arguments for both arguments, millisecond parsing, month-only filtering (#12).
restructured tools to derive from base class BaseCmdLineTool or LogFileTool
fixed bug in logline parsing when detecting duration at the end of a line
changed --log to --logscale argument for mplotqueries to avoid confusion with "log" files
added Contributing page under the tutorials section

This is the first version of mtools that has a version number. Some significant changes to its unnumbered predecessor are:

installable via pip
directory re-organization: All tools are now located under mtools/mtools/. This makes for easier PYTHONPATH integration, which will now have to point to the actual mtools directory, and not to the parent directory anymore. This is more in line with other Python projects.
mlogvis tool added: a simplified version of mplotqueries that doesn't require matplotlib dependency. Instead, it will run in a browser window, using d3.js for visualization. mlogvis is currently in BETA state.
introduced versioning: The version is stored in mtools/version.py and can be accessed programmatically from a Python shell with
```
import mtools
mtools.__version__
```

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