Add PgSQL APT repo and install PostgreSQL 9.3
Install ruby package, don't install docs for gems.
Install ruby-dev, build-essential, ruby-pg, libp5 and libpq-dev in
given order.
Install ruby package, don't install docs for gems.

Fixes #8
Merge branch 'issue-7' into issue-9
Merge branch 'issue-8' into issue-9

Conflicts:
	site.yml
Enable postrgesql.
Merge branch 'master' into issue-10
Add ruby to webservers install.
Merge branch 'issue-9' into issue-10
Install rails globally as ansible default is user.