Bump RSpec to 2.99.0
Convert specs to RSpec 2.99.1 syntax with Transpec

This conversion is done by Transpec 2.3.6 with the following command:
    transpec

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

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

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

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

* 1 conversion
    from: >= expected
      to: be >= expected

* 1 conversion
    from: be_false
      to: be_falsey

* 1 conversion
    from: be_true
      to: be_truthy

For more details: https://github.com/yujinakayama/transpec#supported-conversions
Bump RSpec to 3.0.0

And remove c.treat_symbols_as_metadata_keys_with_true_values = true as
it is deprecated and is now the default functionality in RSpec 3.
Disable RSpec 'should' syntax

The following blog post by Myron Marston explains why the expect syntax
is preferable:

http://myronmars.to/n/dev-blog/2012/06/rspecs-new-expectation-syntax
Merge branch 'rspec-3-upgrade' of https://github.com/alex-tan/fedex into alex-tan-rspec-3-upgrade
Merge branch 'alex-tan-rspec-3-upgrade'