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).
Ok. But I leave the code as it is. Tardyp told me that the best way is to create a directive for this. But I don't know how to do it. It should be done in another PR (or I can cherry-pick it).