Convert specs to the latest RSpec syntax with Transpec

This conversion is done by Transpec 1.4.0 with the following command:
    transpec -m -s --keep deprecated --keep oneliner

* 86 conversions
    from: obj.stub(:message)
      to: allow(obj).to receive(:message)

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

* 25 conversions
    from: obj.stub(:message => value)
      to: allow(obj).to receive_messages(:message => value)

* 8 conversions
    from: obj.should_not_receive(:message)
      to: expect(obj).not_to receive(:message)
Hand convert a few things transpec could not convert.
Enforce the new syntax.
Merge pull request #1202 from rspec/upgrade-syntax

Upgrade syntax