build.sh: Remove unused variable (Never actually implemented)
Simplify and correct build.sh

build.sh should always work (=not need any options to do so), and be not overly slow on new installations (i.e. <30s).
Make installation work again. Probably due to confusion over the two different buildouts, installation failed (Fixes hhucn/adhocracy.hhu_theme#284)
In the future, we may want to simplify the
  system python -> local python buildout -> local python -> adhocracy buildout
chain, preferably to just one or maybe two links.
Remove buildout_offlinemode (-o). This should never have been merged, and was broken by definition (for one, it activated the non-superuser mode without any need to do so). This hhucn/adhocracy.hhu_theme#283
This also fixes an unrelated bug that always created a "1" file; we want 2>&1, not 2& >1.
Delete python/buildout.python/*pyc files in build.sh

Our change 0cfab874e3237c7270f9bfae6b0eb194d5b2b6c5 only works with git 1.7.12.3+ ¹, which is not standard on debian stable.
Alternatively, merging https://github.com/collective/buildout.python/pull/31 would fix the issue upstream.

¹ https://github.com/git/git/commit/8f6811efed5451c72aa