minor doc fix
fix LdaMallet bug where model[vec] returned a corpus
* now a vector on input returns a vector on output as expected
add LdaMallet unit tests
add Similarity method for cleanup in unittests, fixes #182
revert py3k change that breaks dict mixin
up version: 0.9.1
Merge remote-tracking branch 'upstream/develop' into develop
HdpModel.print_topics now has an informative docstring and prints to log.

Resolves #189.