Expose sort and custom queries (instead of using QueryParser)

[casperc]

This commit introduces two new features:

1. It is possible to pass a sort to the search function to have the output sorted. A utility function for creating the most common sorts is provided but it is also possible to create a sort manually and pass it to search.

2. It is possible to pass the search function an instantiated query rather than a string to bypass the query parser. Passing a string works as expected.

[casperc]

PR #19 gives about the same functionality as the first part of my PR, it's a matter of how you want to do it. I prefer the above as it allows the user to bypass the wrapper and make the Sort himself if what the utility function for creating sorts is not sufficient, e.g. creating a custom sort.

2 does pretty much the same, it gives the user the ability make his own query if what the queryparser provides is not enough, rather than preventing it.