Add 'dbshell' argument to manage.py
Add 'dbshell' argument to manage.py

This command is useful when one wants to quickly get into the database.
This is basically a copied version of Django's dbshell command for PostgreSQL.

DocImpact
Change-Id: I731864f943ae1293b93efa422e6de072fe342c0e

nebril/fuel-web,huntxu/fuel-web,stackforge/fuel-web,huntxu/fuel-web,SmartInfrastructures/fuel-web-dev,prmtl/fuel-web,prmtl/fuel-web,SmartInfrastructures/fuel-web-dev,zhaochao/fuel-web,stackforge/fuel-web,eayunstack/fuel-web,zhaochao/fuel-web,nebril/fuel-web,zhaochao/fuel-web,nebril/fuel-web,nebril/fuel-web,zhaochao/fuel-web,eayunstack/fuel-web,nebril/fuel-web,prmtl/fuel-web,eayunstack/fuel-web,eayunstack/fuel-web,eayunstack/fuel-web,prmtl/fuel-web,huntxu/fuel-web,zhaochao/fuel-web,huntxu/fuel-web,SmartInfrastructures/fuel-web-dev,prmtl/fuel-web,stackforge/fuel-web,huntxu/fuel-web,SmartInfrastructures/fuel-web-dev,SmartInfrastructures/fuel-web-dev