Convert specs to RSpec 2.14.8 syntax with Transpec

This conversion is done by Transpec 1.10.4 with the following command:
    transpec

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

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

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

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

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

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

* 2 conversions
    from: obj.should_not_receive(:message)
      to: expect(obj).not_to receive(:message)
Avoid using "should" in example descriptions
Only allow RSpec's new "expect" syntax
Use simplecov instead of rcov for all Rubies, since we have dropped 1.8 anyway
Set up simplecov (it was in the Gemfile before, but it wasn't actually used)
Merge pull request #95 from nicolasmccurdy/use-expect-syntax

Use expect syntax
Merge pull request #96 from nicolasmccurdy/fix-simplecov

Fix simplecov
Replace any system calls in lib that don't use git with calls to FileUtils
Replace a system call in the spec helper
Start using rugged for commands that don't need to show git output
Use Rugged instead of the ` syntax for shell calls
Use rugged instead of system in the spec helper