BUG Message class had columns and relations with same name

Code inherited from old Review class had both columns and relations with
the names 'author' and 'approved_by' so columns have had '_users_id'
appended to them. Related class User along with fixtures and tests
updated accordingly.
add mathod 'name' to User class

This is just a short-cut which returns both first_name and last_name as
a single string.