Adjust factory method to follow Flask extension guidelines
Adjust test for `init_app`
Adjust factory method to follow Flask extension guidelines

Based on 85cdf6bbb968debfa622ccb819ee9849b5a94e88 and
21c4ca7968c5da2c8d9fdb7f13774ec50fe062a5, authored by Matt Wright
<matt@nobien.net> @mattupstate
Fix for allowing redirects through to user
Don't use two checks; Just check the base class
Allow callables as type in reqparse arguments
Test serialization from a set to a list.
Normalize spaces.
Add myself to the list of contributors.
Compare sets, not lists.
Add support of sets to list fields.
Fix the problem that blueprint_setup.add_url_rule won't be called when
an flask.ext.restful.Api object initialized with a Blueprint object and
the BlueprintState object was ready.
Fix the add_url_rule just registered once
Added tests for callables as type in reqparse arguments
Merge pull request #162 from bbenne10/ResponseFix

Allow redirects through to user
Add test for redirect handling
Revert to_marshallable_type() change as advised by @skimbrel.
Merge pull request #175 from kdeldycke/set-support-in-fields

Sets not serialized by fields.List
Merge pull request #167 from lyschoening/master

Tweak to #152 so that callables work as regparser type arguments again
Merge branch 'factory-fix' of github.com:singingwolfboy/flask-restful into singingwolfboy-factory-fix

Conflicts:
	flask_restful/__init__.py