Set boto minimum version

For supporting the S3 multipart upload in glance,
set boto minimum version to 2.12.0.

Implements: blueprint s3-multi-part-upload
Change-Id: Id57a3887256a665455fd83d3e8e752a28c5e7659
Add sphinxcontrib-docbookrestapi

Ceilometer would like to use this piece of software to generate its
documentation on api-site.openstack.org.

Change-Id: Iaa84962378eb1cee9edaccd1ba50b6ad020e1d2a
Add oslo-incubator to automatic update

Change-Id: If422761221a21cfc0da08bd905c8e88f08a8fcce
Merge "Set boto minimum version"
Merge "Add oslo-incubator to automatic update"
Merge "Add sphinxcontrib-docbookrestapi"