Optimisation to reduce authorisation times.

Only the Rights matching the supplied resource name, if any, are examined.
Email now syntax checked.
Specs.
Removed obsolete view code and adjusted specs.
Bundle updated. Rails 4.0 specified.
Upgraded to Rails 4.1.
ApiUserAuth created as a DynamoDB table with attributes.
The ApiUser now maintains its ApiUserShadow.
ApiUserShadow#authentications implemented.
Removed delete_all condition in specs.
Added AWS initialisation to spec_helper.rb.
The group_names attribute in Authentications is no longer present in pure authentications, just like the right attribute. It is present, however, in authorizations.
Removed dead code, added other for clarity.
AuthenticationShadow implemented. Used in authorisation, but not yet for authentication.
Removed comment.
Authentications now DynamoDB.
Migrations to generate ApiUserShadows and to drop the old SQL table for Authentications.
Added rescue clause to SQL table drop.
Guarding for completely empty DynamoDB tables.
Initialised Authentication#username properly.