Fixed psql ALTER USER line for debian
Moved mkdir of tmp_dir in initialize_dirs()

+ stored absolute output in global tmp_dir variable
Moved createdb SQL in separate file to support debian

On debian sudo is not installed by default, this solution avoids using
sudo, is cleaner and more readable
Better look & feel of messages and output

* use hide('everything') in place of hide('stdout', 'stderr')
* shows only relevant bits
* slightly improved messages in output