First import of fasthadd spec file

Compared to @deguio version in #883 this has the following fixes:

- Actually compiles fine.
- init.sh / init.csh files provided. Source those to have a
  consistent, standalone, environment.
- Include in cmssw-tool-conf to make sure this gets built with
  every IB (can still be deployed separately).
Merge pull request #891 from ktf/fasthadd

First import of fasthadd spec file.