Pull request creating Meetup OmniAuth Rails Example App

[MarkDBlackwell]

Adds to the RailsApps OmniAuth authentication menu the option of using Meetup.

Corrects issue #216 so now any preferred OmniAuth provider replaces the default (Twitter) in tests.

Creates a new preference, 'collect_user_email.' If false, this strips all email-related code which otherwise runs during user registration from any generated OmniAuth Rails Example App.

Creates a new Rails Example App, 'rails3-mongoid-omniauth-meetup,' which:

• Utilizes OmniAuth Meetup authentication; and
• Doesn't collect users' email addresses.

Alters the tests from 'rails3-mongoid-omniauth' for the new Rails Example App.

BTW, as of yet, generating the new Rails Example App draws no code from itself. Instead, similar code is drawn from existing Rails Example App, 'rails3-mongoid-omniauth.'

The new app was tested using ERB. No attempt has been made (yet) to remove (if requested) the user registration email-related functionality from the Haml or Slim view translations. That would seem to require something more subtle in the copy_from_repo method.

With that caveat, all gem, 'rails_apps_composer' tests pass, and it generates the RailsApps template with no error messages.

All tests pass in the following Rails Example Apps (and they generate with no error messages):

• The new Rails Example App;
• Existing Rails Example App, 'rails3-mongoid-omniauth.'

The two regenerated Rails Example Apps (above) seem to work fine, and browser login and logout succeeds.