Convert specs to RSpec 2.99.0 syntax with Transpec

This conversion is done by Transpec 1.12.0 with the following command:
    transpec

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

* 2 conversions
    from: obj.should_not_receive(:message)
      to: expect(obj).not_to receive(:message)

* 2 conversions
    from: obj.should_receive(:message)
      to: expect(obj).to receive(:message)
Cleanup whitespace

Signed-off-by: Alex Coles <alex@alexbcoles.com>
Merge pull request #4 from finnlabs/fix/whitespace-cleanup

Cleanup whitespace
Adapted gemsepc dependencies to new version scheme
Remove obsolete openproject-plugins dependency

Signed-off-by: Alex Coles <alex@alexbcoles.com>
Remove superfluous comment in engine.rb

Signed-off-by: Alex Coles <alex@alexbcoles.com>
Merge pull request #5 from finnlabs/feature/integrate-op-plugins-plugin

Remove obsolete openproject-plugins dependency
Merge pull request #3 from finnlabs/feature/rspec-299

RSpec 2.99 Upgrade
Adapt version to corresponding OpenProject core version.
Update stable to v4.0.0