Fix Regexp.escape(filter) for Ruby 1.8.

Ruby 1.8 Regexp.escape does not accept symbols like Ruby 1.9, so
we have to explicitly call #to_s on filter to avoid the Exception.
Merge pull request #51 from geoffgarside/ruby18-issue39

Fix Regexp.escape(filter) for Ruby 1.8.
Update the travis.yml file to use gemfiles to test different rails
versions
Bump master to 0.1.6.dev
Make the project works with Ruby 1.8
Fix buggy tests
Current tests are testing stickiness of non-permitted parameters
Test that not permitted is sticky on #except
Test that permitted? is sticky on accessors, mutators, and merges
Set @permitted on new instance when slicing parameters hash
Only run #keep_if mutator tests if #keep_if is available
Merge pull request #58 from bquorning/permitted_is_sticky_on_slice

Permitted should be sticky when calling slice

Closes #57
simplify bundler setup, and raise since Bundler::GemHelper would blow up either way
Merge pull request #60 from grosser/bundler

simplify bundler setup, and raise since Bundler::GemHelper would blow up...
Make rdoc a development dependency
Just make sure we use a mocha version that works
Add Rails 3.0.x support
test rails 3.0
Merge pull request #61 from grosser/rails30

support and test rails 3.0
update dependencies