FIXED #13: Test trend result chart not shown on inherited project

Added extension point RequestInheritanceChecker. Extensions can check
if given URL points to page that needs inheritance.

Added extensions, that allow inheritance in:
 - build page and specific run page (that preserves current behaviour)
 - job main page
 - some trend graphs on job page (test trend, jacoco coverage trend, 
 findbugs trend)
 - dashboard view and dashboard portlets

This fixes issue #13: Test trend result chart not shown on inherited project.
It is also the way that issue #11 can be fixed (but it isn't fixed yet).