Fix token purging for memcache for user token index.

When issuing a new token, purge all expired tokens from the user's
token index list.

New Options:
* max_compare_and_set_retry:
        The number of retries that will be attempted when performing
        an update of the user_record or the revocation-list record.
        This is relevant due to the use of CAS (compare and set)
        function of the memcache client. This allows for multiple
        keystone processes/wsgi/etc to run without worry of race
        conditions clobbering the lists.

DocImpact - New Options.

Change-Id: I9441105b1e46982b0354bccbf8297daaaa1904b2
Fixes: bug #1171985
Allow request headers access in app context.

- Give extensions access to request headers in app context.
- Implements: blueprint allow-access-to-headers-for-extension.

Change-Id: I22bba172a8ceaba9260487666172586c45aa95d4
Correct the default name attribute for role

Fixes bug1172801

Change-Id: Id2cdc5775bd1b6da03da1e50e84cfe60ada00314
Add checks to test if enabled is bool

  fixes: bug #1167593

Change-Id: Ie18fa17f16383f31d8aa083e69fa501d80eb4553
Using sql as default driver for tokens

kvs driver for tokens is not a production quality storage method.
The shortcomings of using kvs as storage driver for tokens:
    1. It requires load balancer to persist connections to a single
keystone server by token.
    2. The memory will grow out of control until token_flush is run.
    3. At some point kvs lookups get very slow because there are millions
of keys in the dict.
    4. Process restart invalidates all tokens.

Fixes: bug #1188370
Change-Id: Ic726e12d798b843412158a7b92f5e3e3a654811f
Merge "Allow request headers access in app context."
Merge "Fix token purging for memcache for user token index."
Imported Translations from Transifex

Change-Id: I9f027065d4aeaa31fb45274d7664c3920ef40a13
Merge "Add checks to test if enabled is bool"
Merge "Using sql as default driver for tokens"
Merge "Imported Translations from Transifex"
Merge "Correct the default name attribute for role"