Add Ruby 2 to travis
Allow activerecord > v3.0 for rails 4
Allowing to pass scope to previous/next methods
Merge remote-tracking branch 'fny/rails4'
Remove unnecessary argument.
Merge branch 'master' of https://github.com/radar/by_star

Conflicts:
	.travis.yml
	by_star.gemspec
	lib/by_star/instance_methods.rb
Updating ability to scope the `previous` and `next` methods.
Merge branch 'master' into with_scope

Conflicts:
	lib/by_star/instance_methods.rb
Add :day_of_month field to Post class.
- Merge @pnomolos branch 'with_scope'
- Add default scope parameter support
- Support scope as Proc/Lambda
- Fix :field option before/after