Tag 0.12.x release

git-svn-id: https://svn.apache.org/repos/asf/libcloud/tags/0.12.x@1439035 13f79535-47bb-0310-9956-ffa450edef68
Backport commits from trunk.


git-svn-id: https://svn.apache.org/repos/asf/libcloud/branches/0.12.x@1457201 13f79535-47bb-0310-9956-ffa450edef68
Bump version.


git-svn-id: https://svn.apache.org/repos/asf/libcloud/branches/0.12.x@1457202 13f79535-47bb-0310-9956-ffa450edef68
Merge remote-tracking branch 'upstream/0.12.x', tag '0.12.x' into 0.12.x

0.12.x