List all changes related to a build.

 - to do this, the column 'parent_changeid' was added to the table changes

Note:
 - I added a tab 'changes' for the build webpage. I think this should be modified in order to have something more readable (but my angularJS skills are very limited).
(nit) can you shrink that line a little?  Maybe with a lambda?  I'll take a bit of the blame for the ridiculously long dotted path and function names :)