Return Symbol in find_scope! if String passed
Removes reloading of routes when eager loading ...

... is enabled.

The old code may cause conflicts when developing an engine (i.e. invalid
route name) and according to @josevalim the reason for it to remain is
unknown.
Merge pull request #3171 from micat/find_scope-should-accept-string

Url helpers raise "undefined method `router_name' for nil:NilClass"
Merge pull request #3195 from fgro/master

Removes reloading of routes when eager loading ...
Set null: false explicitly in timestamps
Fix docs for http_authenticatable_on_xhr, closes #3112
Decouple validation from remember_me in authentication strategies

Closes #3118