More logging to try and establish why polling dies.
Make sure we never propose an interval of 0 milliseconds.

Doing so causes RX to blow up as it winds up as a NullPointerException down in java.util.concurrent.ScheduledThreadPoolExecutor.scheduleAtFixedRate
Merge pull request #178 from guardian/pw-fix-observables

Fix the issue where polling would die after a certain period
Only query for succesful builds
Merge pull request #179 from guardian/pw-only-succesful-builds

Only query for succesful builds
Poll for CloudFormation events to ensure update worked.
Improve CloudFormation deployment type's documentation
Only add Stage parameter if necessary
Support multiple stacks properly

Defaults to prepending a stack name where available and adds a parameter of the stack if in the list required by the template.

I've also made everything explicit about talking about CloudFormation stacks, which is horribly verbose, but I fear necessary.
Merge pull request #180 from guardian/pw-check-cloud-formation-events

Check cloud formation events
Minor correction to documentation
Handle stop flag in CloudFormation update.
Additional documentation
Avoid race condition when previewing

Under load, send might not have completed when the preview content template attempts to render resulting in an exception.  I've seen this happen a number of times.  By blocking on the update of the available previews we can avoid this.  There are definitely more heinous examples of blocking around in RiffRaff, so I'm not too worried about this one.
Merge pull request #181 from guardian/pw-handle-stop-in-update-cloud-formation

Handle stop flag in CloudFormation update.
Merge pull request #182 from guardian/pw-preview-race-condition

Avoid race condition when previewing
Update to work with Teamcity 8

Unfortunately, have to rely on the 'experimental' fields parameter (http://youtrack.jetbrains.com/issue/TW-26176)
Merge pull request #183 from guardian/pw-teamcity-8

Update to work with Teamcity 8
vcs-root-id is now a string

Also now log an error if we fail whilst retrieving VCS details
Merge pull request #184 from guardian/pw-vcs-root-as-string

vcs-root-id is now a string