Updates to make the build environment check more reasonable:
Mercurial v1.3 permitted
The Java compiler is not a showstopping issue
7-zip can be installed in any location
Update to Helium 5
Helium can be installed in PDT 1.*, not necessarily 1.0
Raptor installation path not significant
Update to Raptor 2.9.*
The Raptor patch to update the bundled version of python is no longer relevant
BRAG calculations updated to ignore items not being in the system path, as this just doesn't matter.
Overall effect is that the build environment check should pass on a machine that is able to do a build!
