explained the use of DB::expr() when using literals in a join
Updates develop branch version number.
is_frozen() doesn't exists, corrected to frozen()
Merge pull request #571 from Art4/1.7/develop

is_frozen() doesn't exists, corrected to frozen()
documented Input::patch()
second parameter of Config::save() is not optional
clarified the difference between PUT and PATCH;added a note that all HTTP methods are supported