Connect to Postgres on localhost

* Most installs listen on localhost
* Many installs do not listen on a socket
* This fixes connection errors for many users
Move SMTP variable settings out of initializer

Since we require the `smtp.rb` file in the environment files, and Rails loads it
as part of its boot process, this file was loaded twice. This causes a constant
reinitialization warning.

Also, to remove the duplicaton, there is no need to check the environment,
since we require the files from the appropriate environment files.

Fixes #335