Changed the version number for PostgreSQL to 9.3
Set the package name for PostGIS using an attribute based on the
version of PostgreSQL being installed.
Added a attribute to specify postgresql version for PostGIS.
Working on a way to use the postgresql version number.
Changed PostGIS version attribute to default to the PostgreSQL version number
Merge pull request #5 from zmaillard/master

Added Support For Multiple Versions of PostgreSQL