Make sure msgpack-python version >= 0.4.0

Now Marconi is using on msgpack and relaying on a new feature
introdcued in msgpack since 0.4.0. If user are using the version
under that, they may run into HTTP 503 code for some operations.

Change-Id: Ib24318c3d593f3d2d0625d0f2c582e26d81f43d1
Closes-Bug: 1331280
Make sure pymongo version >= 2.5

Now Marconi is exposing pymongo's cert options to user for the
maxium security, which was added since version 2.5

Change-Id: I504112d1f39e5a1b74bcae56b4b855c25b47acd8
Closes-Bug: #1328720
Add oslo.db library

blueprint oslo-db-lib

Change-Id: I4fa1beb8dd9a9bbf5c220cf310aa56f407392233
Merge "Make sure pymongo version >= 2.5"
Merge "Make sure msgpack-python version >= 0.4.0"