Add a SUGAR_HOME environment variable

We should really use XDG directories but that will be a bit
more complicated and require migration scripts. This is a
short time solution to "expose" the dot sugar directory in
sugar-build.
Make the debug script profile aware
Remove duplicated code

And deprecate duplicated function.
Remove now unused method
Commit from Sugar Labs: Translation System by user cjl.: 40 of 40 messages translated (0 fuzzy).
Use python2 shebang

Some distributions have switched to python3 as default and our code
breaks because it's python2 specific. Follow the PEP 394
recommendation.
Release 0.99.4