client credentials should be optional (fix #759)

client credentials should only be required on token
request

Signed-off-by: Fernando Rocha <fernandogrd@gmail.com>
Refactored urlize_quoted_links code, now based on Django 1.5 urlize
Added quotes to TRAILING_PUNCTUATION used by urlize_quoted_links
Complete remove of client checks from oauth2

Signed-off-by: Fernando Rocha <fernandogrd@gmail.com>
Remove client credentials from all OAuth 2 tests
Remove oauth2-provider backends reference from compat.py
Added force_text to compat
Cleaned imports on templatetags/rest_framework module
Merge pull request #768 from kevinastone/master

Fixeds DjangoFilterBackend Incompatibility with SingleObjectMixin
Merge pull request #766 from glic3rinu/master

Refactored urlize_quoted_links based on Dango 1.5 urlize
Merge pull request #767 from tomchristie/fix-oauth2-token-only

Fix OAuth 2 token only
Update release-notes.md