Add tags to CI model and implement for TC

Tags can be meaningful in a decision of which build to deploy. This is a fairly simplistic approach to surfacing this information, simply adding it to the branch and date already in the autocompletion - but this is better than nothing.
Add the new CIBuild field to test classes
Merge pull request #193 from guardian/sh-surface-tags

Add tags to CI model and implement for TC
Revert "Add tags to CI model and implement for TC"
Merge pull request #194 from guardian/revert-193-sh-surface-tags

Revert "Add tags to CI model and implement for TC"
Cull instances in order based on availability zone
Make ordering method generic, add tests.
Better transpose method