Update setup.py classifiers

Merge pull request #98 from matiasb/release-0.7.4

Prepare release 0.7.4

Merge pull request #92 from matiasb/update-version-0.7.3

Update version for release 0.7.3

Update version for release 0.7.2

Merge pull request #88 from matiasb/preparing-release-0.7.1

Update version for release 0.7.1

Update travis badge in README

Merge pull request #72 from matiasb/preparing-release-0.6.0

Prepare 0.6.0 release.

Merge pull request #49 from matiasb/preparing-0.5.5

Minor updates preparing release.

Updated/fixed changelog.

Re-release as 0.5.3.