Make add-fixed-ip update nwfilter wth in libvirt

Add inject_network_info to the libvirt driver  so that the
add-fixed-ip call will trigger a refresh of the nwfilters.

Change-Id: I00eccf34b8f92fb1e26a72e4bddb47dd39c4558f
Fixes: bug #1124722
Merge "Make add-fixed-ip update nwfilter wth in libvirt"
Move DB thread pooling to DB API.

The eventlet db_pool wrapping done in sqlalchemy is wrong.  It needs to
be around the whole DB API call.

Fixes bug 1128605

Syncs nova with the fix in oslo.  Moves nova to use the oslo version of
db/api.py to import the DB API implementation.

Renames configuration option sql_dbpool_enable to dbapi_use_tpool

NOTE: tpool will not work without a fix to eventlet for Threads + locking.

DocImpact

Change-Id: I6c75b6138d38d12261d133f2cb2f5e59c667f837
Merge "Move DB thread pooling to DB API."