Use simplecov for coverage reports for specs and cucumber

simplecov is a wrapper on the built-in coverage library for Ruby 1.9+.  When running `rake spec` or `rake cucumber`, a coverage report will be output in coverage/index.html.  If you run both tasks or all tasks with `rake spec` within a close enough time window (I think 10 minutes) the results will all be merged so you can get coverage across both the specs and features.  If this PR is accepts, then I'll add another to use coveralls.io to publish the coverage reports to coveralls.io, but someone with admin access will have to setup the hooks on coveralls.io for that.  Additionally, the reports from simplecov are a confirmation that not all steps are being exercised, include the ones dealing with rvm.  I have a fix for that too that I can post in a later PR.

![screen shot 2014-09-25 at 2 04 16 pm](https://cloud.githubusercontent.com/assets/2230482/4410585/09ea8eb6-44e7-11e4-9572-f7f83ba28451.png)

# Verifications Steps

## specs

- [ ] `rake spec`
- [ ] VERIFY no failures
- [ ] `open coverage/index.html`
- [ ] VERIFY coverage report includes specs
- [ ] `rm -rf coverage`

## cucumber

- [ ] `rake cucumber`
- [ ] VERIFY no failures
- [ ] `open coverage/index.html`
- [ ] VIERFY coverage report includes features and steps
- [ ] `rm -rf coverage`

## all

- [ ] `rake`
- [ ] VERIFY no failures
- [ ] `open coverage/index.html`
- [ ] VERIFY coverage includes specs, features, and steps