release stage: Actually release the stories

release stage is now actually releasing the affected stories, which is
what was forgotten in the original implementation of release stage.

The command was also a bit refactored and improved. The push step is not
the last step any more, the story release step is the last step now. In
case there is an error in the issue tracker release step, the user is
asked to fix the inconsistencies manually. This is easier than rolling
back after failing to push. And the API calls should mostly work just
fine, all conditions are checked before the push, so the last them is
just about performing the API call to modify the stories.

Change-Id: e61190c344
Story-Id: SF-78
git: Pull "unassigned" Story-Id value into const

Make this special Story-Id tag value a const, not just a string
hard-coded throughout the code base.

Change-Id: c252361293
Story-Id: SF-77
jira/client: Parse JIRA error message properly

Story-Id: SF-90
Change-Id: e125b18c86
Bump version to 0.5.0

Story-Id: unassigned
Change-Id: e83a4430bf
jira/api: Be more clever with JIRA API errors

In case some of the issue IDs in listStoriesById is not found, return at
least the issues that were found together with the error. This means
that it is now possible to do something with the partial result in case
that err != nil && len(issues) != 0.

Change-Id: 06acda1b15
Story-Id: SF-77
hooks/pre-push: Make the hook a bit more clever

Relax the conditions that lead to the commits being pushed to be checked
for Change-Id and Story-Id. The check is actually taking place now only
if there is some other commit with the relevant tag that is an ancestor
of the commit being checked.

This change is introduced to make it possible to start using SalsaFlow
on older projects where the tags are missing and it's not possible to
fix it really.

Change-Id: eba241960e
Story-Id: SF-89
story start: Mention how to cancel the process

The story prompt now mentions that pressing Enter will abort the process.

Story-Id: SF-91
Change-Id: b4f863974d
reviewboard: Print hint when rbt --version fails

Change-Id: 412d41349e
Story-Id: SF-11
hooks/pre-push: Do not check the tags too soon

Fix an issue with a missing conditional. The tags were being checked
even though they were not supposed to be checked.

Change-Id: 55f4baa47f
Story-Id: SF-89
review post: Improve the followup message

Change-Id: 1c5ae658fc
Story-Id: SF-76
review post: Format error message better

Improve formatting for the scenarion when there are no stories that the
unassigned commits can be assigned to.

Change-Id: 395c9f4a83
Story-Id: SF-80
vendoring: Commit Godeps for the first time

Story-Id: SF-95
Change-Id: d4c69a2856
CircleCI: Update circle.yml to use vendoring

And also extend the Makefile a bit to use vendoring.

Change-Id: 07a72d38ae
Story-Id: SF-95
jira: Rename configuration keys

Local config:
  jira.base_url -> jira.server_url

Global config:
  jira.credentials.base_prefix -> jira.credentials.server_prefix

Change-Id: 2e56d2be95
Story-Id: SF-96
git: Make case insensitive matching nicer

Rename GrepCommits to GrepCommitsCaseInsensitive and add
--regexp-case-insensitive flag when calling git.

Change-Id: e973546cb4
Story-Id: SF-84
jira: Explain stageableStateIds

Story-Id: SF-84
Change-Id: 65430eef5b
prompt: Delete Pivotal Tracker-related code

There was some unused code there, that was anyway not supposed to be
there. It goes into the PT module and it will be re-implemented in case
Pivotal Tracker becomes a supported issues tracker.

Story-Id: SF-98
Change-Id: 8b7ba5263b
Transfer the repo to salsaflow GitHub org

This requires the import paths to be fixed, and that is exactly what
this commit takes care of.

Change-Id: e9e53400a9
Story-Id: SF-98
Update README so that it contains meaningful stuff

Change-Id: 0eae768d00
Story-Id: SF-94
jira: config: Rename base_url to server_url

And add proper validation to JIRA credentials.

Change-Id: f3ec76b888
Story-Id: SF-96