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
Update README.rdoc

Update Singleton section of Readme, to accord undocumented yet changes (https://github.com/josevalim/inherited_resources/commit/cfb2d88c6d93dbaf9bd4a81996a660181fd2b2e1 - Allow for nesting of singleton belong_to's.)
allow permitted_params to be a private method

The examples in the strong_parameters README show a private method
for parameter sanitization.  This tiny change allows for following
that pattern.
typo fix
Don't call :scoped if it's deprecated.
Merge pull request #272 from tab/master

typo fix