Modified and renamed build bash script.

The main change has been to allow PyInstaller to be run within
the debian packaging toolsets fakeroot environment.

The issue is documented here:
https://groups.google.com/forum/#!topic/pyinstaller/1hMHuruPlro

The workaround is a refinement of the suggestion.
Added basic debian changelog.
Tidying debian rules and correcting typos.
Moved PyInstaller calls to a separate shell script.

Also moved all build artefacts to one sub dir for easier cleaning
and change clean to reflect this.
Changed travis build to try to make debian package.

This is experimental, as it's difficult to test until a real
Travis CI box builds it.