Fix issue #190 and #195

This resolves issues where an integer column would raise an exception
when handled by Ransack::Constants.escape_wildcards.
Change RSpec configuration alias

In RSpec, v2.8, RSpec::Core::Configuration#alias_it_behaves_like_to
does not exist. This method is introduced in later versions. Instead,
use RSpec::Core::Configuration#alias_it_should_behave_like_to.
Use Object#send to comply with Ruby 1.8.7
Merge pull request #196 from KevinSjoberg/master

Fix issue #190 and #195