Adding PostgreSQL 9.3 support for Ubuntu 14.04

- Added conditional support for PostgreSQL 9.3.
- Added conf_dir and create_cluster variables to denote actions based on
  OS / release.
Fixing issues with Centos (initdb, and service name).
Removing the static 9.3 from init.sls, moving it to a variable.
Merge pull request #19 from berry-langerak/bugfix/adding-postgresql-9.3-support

Adding PostgreSQL 9.3 support for Ubuntu 14.04