Update dependency info in README.
Merge commit.
Fix trove classifiers.

Quoted from:

    In order to show up on the list of projects that support Python 3,
    the project needs to set the Programming Language :: Python :: 3
    trove classifier.

http://nothingbutsnark.svbtle.com/my-experience-creating-caniusepython3
Merge pull request #4 from berkerpeksag/minor-updates

Fix trove classifiers.
Merge commit.
Update changelog for 2.2. release.
Added tag v2.2 for changeset 513da1aa44d5
Update Python dependency version in README.