Add database management support

Adding the puppet-postgresql, puppetlabs-mysql, stdlib and concat modules.
The existing concat module is renamed to prevent a conflict and since it's
types/providers, the name doesn't matter.

Clarifying the licensing statement as these are Apache 2 licensed modules.

This depends on https://github.com/theforeman/puppet-foreman/pull/51.  It also renames a couple of submodules, which is a bit hairy, so be careful.  To test it, do the following:

1. fetch my puppet-foreman branch in the foreman submodule
2. fetch my foreman-installer branch here
3. run `git submodule sync`
4. run `git submodule update`
5. hope that git doesn't blow up

I've only tested this on RHEL6, so would appreciate some Debian and Ubuntu testing - though I expect both of the modules are in good shape for those systems.

Currently the postgresql submodule points at my fork, but I'll fix that once one more PR is merged into upstream for Puppet 2.6 compat.