git: Remove the story branches stuff

It is no longer needed since we don't put story IDs into the branch
names any more.

Change-Id: cfcb66ea19
git: Add StoryIds function, fix and improve stuff

StoryIds returns the list of unique non-empty Story-Id tag values for
the given list of commits. In case the tag is "unassigned", it is
ignored.

Change-Id: 7d173d356e
prompt: Extract story listing in ListStories

Change-Id: 6c0181f1c6
scripts: Add validation to LocalConfig

Make scripts.{get,set}_version a required config field.

Change-Id: 936f90c405
version: Add functions to get from/set for branch

GetByBranch can be used to get the version string from a branch.

SetForBranch will set version for the given branch.

Change-Id: ebdf1d362d
releases: Add a package with release utils

For now there is just ListNewTrunkCommits, which can be used to get the
commits that were added since to trunk since the last release tag.

Change-Id: 0af59af656
Some silly file renaming

Change-Id: 9fb00c1a12
jira/client: Add Client.Projects.ListVersions

Change-Id: 6eedff5c3d