Merge pull request #23 from Takadonet/master

Bug fix for Issue #22
Bump version
Modify approach to finding placement for a new instance to be more accurate (i.e., look at the given cluster's persistent data to determina appropriate placement zone). Also add a couple of methods to retrive cluster's persistent data. Chnaged singnature of _find_placements method to find_placements.
Bump dev version
Merge pull request #25 from Takadonet/master

Enable updating history name and annotation metadata
Merge pull request #26 from Takadonet/master

Ability to add a new history tag
Placement detection tweak
Bump version
Improve docstrings for a few methods in CloudManLauncher class
Include bucket_name in clusters' persistent data dict (get_clusters_pd method)
Bump version (to v0.3.1)