1.5.1 prep.
Merge pull request #328 from mhaskel/1.5.1-prep

1.5.1 prep.
Prepare a 1.5.2 release.
Merge pull request #331 from apenney/152-release

Prepare a 1.5.2 release.
Merge remote-tracking branch 'upstream/1.5.x'
Merge pull request #334 from mhaskel/1.5.x-merge

1.5.x merge