changes attr_accessible to attr_accessor

* fix for rails 4
* attr_accessible not needed for usage
updates to gem version 0.7.3

* updates dependencies to rails 4 and devise 3.0.0
removes attr_accessor
updates attribute handling for rails 4

* uses strong parameters
uses strong parameters in password_expired_controller
Merge pull request #56 from angrauel/master

fixes for rails 4