Add an empty folder for building in

Achieve 3 things:
- a folder for Eclipse project to build in, allowing
  to provide cleaner Eclipse .project / .cproject
- a folder for automake users to build in
- build artefacts won't show up in git as new files

Since .gitignore is in the folder, it isn't empty.
Since everything but .gitignore is ignored, nothing
in it will ever show up.
Add final newline
Merge pull request #410 from arstrube/cpputest_build

Add a folder for building in