Add the ability to load icons from a zip archive.

[srbaker]

Not sure if this is of high quality or not, but it works to solve #3.

[coveralls]

Coverage decreased (-4.8%) to 95.161% when pulling 4bde062 on srbaker:add-zip-support into 80bd62b on peteruhnak:master.

[peteruhnak]

Can you add test(s) for this please?
It works today, but we want to make sure it also works tomorrow. :-)

[srbaker]

Of course! Still learning my way around. :)