Deleted git branches show in branch selector

Related to FECRU-1321

When a git branch is deleted, it is not removed from the BranchDao, meaning it still shows up as a completion in the graph branch selector.

The code here: https://extranet.atlassian.com/crucible/browse/FE-hg/src/java/com/atlassian/fisheye/git/GitScanner.java?hb=true#l438 Should be calling this: https://extranet.atlassian.com/crucible/browse/FE-hg/src/java/com/cenqua/fisheye/cache/BaseRevisionCache.java?hb=true#l903 (which currently is not called from anywhere according to Idea).