Convert specs to RSpec 2.14.7 syntax with Transpec

This conversion is done by Transpec 2.2.0 with the following command:
    transpec tests/ruby

* 6 conversions
    from: obj.should_receive(:message)
      to: expect(obj).to receive(:message)

See also: https://github.com/yujinakayama/transpec#supported-conversions
version + changelog
Merge pull request #116 from yast/rspec-expect

Converted "should" to "expect" in RSpec.