postgis: module parametrization

Massive code cleanup using far less classes but with a parameter for
the postgresql version.

Include classes for redhat support (not actually implemented) and removed
ancient ubuntu support.
Merge pull request #8 from ckaenzig/params

postgis: module parametrization
missing support for 9.1 in make-postgresql-postgis-template.sh
basic error checking on postgis template creation.
Merge pull request #9 from mfournier/fix-template-script

Fix template script