Qt Metrics v2.8: Build phases graph

Added a graph to visualize the project build phases by configurations.
It shows how long do the builds take to execute, and are the different
configurations run effectively in parallel. Graph is implemented with
the D3 graphics library. Data is read from the phases and phases_latest
database tables.

Change-Id: I51991a264ceb97e6b4d12df0d10e8c9f46a2faa0
Reviewed-by: Tony Sarajärvi <tony.sarajarvi@digia.com>