Travis configuration to test amagama (minimally)

install other dependencies (simplejson for python<2.6, Flask-Script)
get PYTHONPATH from python sys.path, not environment
create amagama postgres db
install sphinx and test build (html) docs
run a few amagama-manage commands
always notify on failure

fix amagama-manage to avoid flaskext_compat problems on newer flask (>0.8)