Add FULL_BUILD_VERSION

Fix the git_commit_hashes hook, so the pre-release number is added to `AssemblyInformationalVersion`, not the `AssemblyVersion`.

![image](https://cloud.githubusercontent.com/assets/119081/5487375/d951c1bc-86a8-11e4-8227-33be37d3f702.png)

:mag: @lukesmith 
I think it should be `BUILD_VERSION_FULL` for parity with the `GIT_HASH` pair. Also, means they'd be adjacent in an alphabetic list.