Do not call --unshallow from full repos.

Fixes #65.
Merge pull request #66 from rjackson/fix_issue_65

Do not call --unshallow from full repos.
Make static test site.

Running the following from the ember repo should result in a static file
to run the test suite on (make sure to run `rake dist` first):

```ruby
require 'bundler/setup'
require 'ember-dev'

generator = EmberDev::TestSiteGenerator.new(static: true)
generator.save('dist')
```