Config autogeneration

[COOK-2390](http://tickets.opscode.com/browse/COOK-2390) - Recipes to auto-generate many postgresql.conf settings, following "initdb" and "pgtune"

I've written two recipes to auto-generate many postgresql.conf settings. I derived them from the source code of a couple important PostgreSQL utilities:

`initdb` – initializes the database cluster’s default locale and character set encoding. (See the original [initdb source code](http://doxygen.postgresql.org/initdb_8c_source.html).)

`pgtune` – takes the wimpy default postgresql.conf and expands the database
server to be as powerful as the hardware it's being deployed on. (See the original [pgtune python script](https://github.com/gregs1104/pgtune).)