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.

Refactor define_restrict_dependency_method using reflection

Remove sort on attributes.keys

Make the method API more clear by explicitly showing the expected
arguments. This means that the options cannot be passed as second
argument because we are not relying on extract_options! anymore,
you are expected to give a selected key or `nil` if you want to pass
options, as it is the last argument.

Notice that this does not change the current method arguments contract
available in 3.2, it just brings back the same functionality with the
divider addition.

`class_attribute` already generates instance readers/writers by default,
so there's no need to add delegation methods.

Removes some "method redefined" warnings.

This reverts commit 23a98ffb.

[ci skip]

Minitest uses different signature for assert_no_match, so we have to
swap arguments.

The fix commited in e2a070cf was returning the `new_target`, as
a try to return whatever user replaced association with. The
problem is, the resulting association target may be ordered
differently. In such case we want to return the target that
will be later used for that association.