Add script to ensure semantic versions work with continuous build.

This module generates and inserts a patch component of the semantic version
stamp for Barbican, intended to ensure that a strictly monotonically increasing
version is produced for consecutive development releases. Some repositories
such as yum use this increasing semantic version to select the latest
package for installations.

This process may not be required if a bug in the 'pbr' library is fixed:
https://bugs.launchpad.net/pbr/+bug/1206730

Change-Id: I19623d76b161331c2033ea129e7f3f67518520fa
Merge "Add script to ensure semantic versions work with continuous build."