This reverts commit feaa7b35.

Reason: Incorrect change. That's a Rails 4 feature and will not
obviously work in 3.2.3.

[ci skip]

This reverts commit fa6d921e.

Reason: Not a fan of such massive changes. We usually close such changes
if made to Rails master as a pull request. Following the same principle
here and reverting.

[ci skip]

This syntax does not seem to work. Throws the error
  "can't convert String into Hash (TypeError)"

Tested on:
* Ruby 1.9.3
* Rails 3.2.3

This comment about :env option for gem method was actual for rails 2.3
without bundler. Now bundler uses grups for this goal.

For future reference, this is the regex I used: ^\s*#\s*\n(?!\s*#). Replace
with the first match, and voilà! Note that the regex matches a little bit too
much, so you probably want to `git add -i .` and go through every single diff
to check if it actually should be changed.