Removed unused use statement
Merge pull request #4631 from GrahamCampbell/4.1-router

[4.1] Removed Unused Use Statement
:fix dockblock for whereNull
Add contains method to base collection
Not passing  to model constructor
Merge pull request #4976 from JosephSilber/remove-columns

Not passing columns to model constructor
Merge pull request #4974 from JosephSilber/collection-contains

Add contains method to base collection
Fix order of methods.
Merge branch '4.1' into 4.2
Add JoinClause whereNull unit test
Merge branch '4.2' of https://github.com/laravel/framework into join_where_null
Merge branch 'join_where_null' of https://github.com/ambrella/framework into join_where_null