Ensure we use Berkshelf ~> 2.0.10 (requires Thor, thus the Thorfile)

Some errors w/ Berkshelf (esp. w/ Test Kitchen) are resolved in this manner
Lock apache2 cookbook version to 1.6.6 for testing

The later version of the apache2 cookbook seem to have some bugs that
have been introduced, namely w/ some duplicate config files being created.

See https://tickets.opscode.com/browse/COOK-3821 for this
specific issue.

See https://tickets.opscode.com/secure/IssueNavigator.jspa?reset=true&jqlQuery=project+%3D+COOK+AND+component+%3D+apache2+AND+resolution+%3D+Unresolved+ORDER+BY+priority+DESC%2C+key+DESC&mode=hide for all unresolved apache2 cookbook issues.