Add missing default values for oauth tables

- Give oauth_clients/oauth_authorization_codes redirect_uri a default value
- Default value for created
- Default values for scope and grant_types
Move oauth table created migration into the koauth module
Fix Migration_Oauth2_0_1_20140310135458::down()

The minimum value for TIMESTAMP is 1970-01-01 00:00:01
so we have to handle created = 0 differently
Explicitly add redirect_uri value's in Base.yml