Stream-python

* Added support for Python 2.6.9 and downgrade to requests 2.2.1

* Fix errors_from_fields function so it displays the extra data returned by the
server about InputException errors.

* Add support for keep_history on unfollow

* Add HTTP Signature auth method (for application auth resources)
* Add support for follow_many batch operation
* Add support for add_to_many batch operation
* Decode JWT from bytes to UTF-8
* Skip add_activities API call if activity_list is empty
* Fix feed group and id validation, dashes are now allowed

* Added support for activity update

* Added support for creating redirect urls