Merge branch 'release-0.1.2'
Merge branch 'release-0.1.3'
Merge branch 'release-0.1.4'
Merge branch 'release-0.1.5'
Merge branch 'release-0.2'.
Depend on a specific version of tweepy.

The latest version (3.0) seems to be uninstallable as of Dec. 1st.
Update version number and changelog for ztreamy 0.2.1.
Merge branch 'hotfix-0.2.1' into development.