Remove rspec from Gemfile since rspec-rails includes rspec
Update Gems
Go back to transistional rspec 2.99 for smooth upgrade.
All unit tests pass now but many deprecation warnings.
Convert specs to RSpec 2.99.2 syntax with Transpec

This conversion is done by Transpec 2.3.7 with the following command:
    transpec

* 346 conversions
    from: obj.should
      to: expect(obj).to

* 121 conversions
    from: == expected
      to: eq(expected)

* 52 conversions
    from: obj.should_not
      to: expect(obj).not_to

* 40 conversions
    from: =~ /pattern/
      to: match(/pattern/)

* 21 conversions
    from: lambda { }.should_not
      to: expect { }.not_to

* 16 conversions
    from: describe 'some view' { }
      to: describe 'some view', :type => :view { }

* 15 conversions
    from: describe 'some controller' { }
      to: describe 'some controller', :type => :controller { }

* 15 conversions
    from: describe 'some model' { }
      to: describe 'some model', :type => :model { }

* 15 conversions
    from: pending 'is an example' { }
      to: skip 'is an example' { }

* 10 conversions
    from: lambda { }.should
      to: expect { }.to

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

* 3 conversions
    from: describe 'some helper' { }
      to: describe 'some helper', :type => :helper { }

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

* 1 conversion
    from: describe 'some mailer' { }
      to: describe 'some mailer', :type => :mailer { }

* 1 conversion
    from: describe 'some request' { }
      to: describe 'some request', :type => :request { }

* 1 conversion
    from: describe 'some routing' { }
      to: describe 'some routing', :type => :routing { }

For more details: https://github.com/yujinakayama/transpec#supported-conversions
Update unit tests to conform to Rspec3.
All test pass now.