updated AR#create! to accept an options hash so the mass-assignment security role can be passed in, also updated the Changelog to mention the change to some of the AR method signatures.

singular and collection relations in AR can now specify mass-assignment security options (:as and :without_protection) in build, create and create! methods.

fix mass-assignment security tests, this was due to a string column limit which doesn't cause issues on sqlite

Added assign_attributes to Active Record which accepts a mass-assignment security scope using the :as option, while also allowing mass-assignment security to be bypassed using :with_protected

Signed-off-by: NJosé Valim <jose.valim@gmail.com>

Signed-off-by: NJosé Valim <jose.valim@gmail.com>