PluginBase: don't read current branch state when committing results
PluginBase: don't read current branch state when committing results

It does not help:
1. In the old code, there is a race between getBranchNames and setBranchHash, so we need to handle the failure case properly anyway
2. getBranchNames adds round-trips and slowness


Former-commit-id: 5002d04b9c6f56432753e3c7b2774cabc742ed71
webgme/webgme-engine,webgme/webgme-engine,webgme/webgme-engine