Allow for nesting of singleton belong_to's.

Note that
    class ThingAController < InheritedResource::Base
        belongs_to :thing_b, :singleton => true
    end
used to mean there was only one ThingA (so resource_path == /thing_bs/123/thing_a), while it now means there is only one ThingB (so resource_path == /thing_b/thing_as/123)

To specify there is only one ThingA, you'll need
    defaults :singleton => true
update pr #194 to merge cleanly
fix multi-level nested singletons like /object/:id/thinga/thingb
add strong parameters test
support strong parameteters via permitted_params method
add strong parameters support to readme
Fix Readme typo
Merge pull request #267 from BlackFoks/master

Fix Readme typo
Merge pull request #260 from taavo/strong_parameters

Integrate with strong_parameters
Merge pull request #258 from stephenprater/pull_request_194

Pull request #194
Bundle update
Updated CHANGELOG
Release 1.4.0
Add license to gemspec

Prior to this commit, the gemspec did not include the license, which
means that one can't use the rubygems API to automatically determine
licensing of vendored gems. This commit adds the licensing to the
gemspec.
Merge pull request #268 from jeffweiss/master

Add license to gemspec
Merge remote-tracking branch 'upstream/master' into rails4

Conflicts:
	Gemfile
	Gemfile.lock
Update Gemfile.lock after upstream merge