Added repos for new fabric and ubuntu-cloud-archive in sources.list of lb, fixed the order of networks connected to compute ndoes

There are two fixes here


1.     Added repos for new fabric and ubuntu-cloud-archive in sources.list of lb
    
    Fabric version in ubuntu repos are older version which lacks some required features.
    So added chris-lea ppa for newer version of fabric and added ubuntu-cloud-archive for
    python-paramiko version which is required for new fabric.

2. Fixed the order of networks connected to compute nodes
    
    All nodes must have stgaccess_network connected to its first nic.
    For compute nodes eth0 was connected to sdn network, so changed it.