Created savanna-db-manage script for new DB

 + Couple of minor adjustments

Change-Id: I4e43d138b23904a02deb7d15b28e4960494ee976
Update requirements to the latest versions

* pbr 0.5.21 includes all savanna-related fixes
* next major release of sqlalchemy allowed

Change-Id: Ib47408dc217fad1c97b623ce0557d9d4f6da0e16
Merge "Created savanna-db-manage script for new DB"
Merge "Update requirements to the latest versions"