Updates to Travis-CI build to fix Ruby 1.8.7 builds and enable Ruby 2.0.0/Rails 3.2.0 build

Change adds workaround for failing build on Ruby 1.8.7:

* https://github.com/bundler/bundler/issues/2780
* https://github.com/bundler/bundler/issues/2784
* https://github.com/rspec/rspec-expectations/commit/d2e3d97e5f0f1e23061f26376d2a752292c2a5d2

Change also enables Ruby 2.0.0/Rails 3.2.0 build since there is no reason this should not be supported. .gitignore now also ignores .bundle and .ruby-version.