Add upgrade pip command to QuickStart Doc
Add upgrade pip command to QuickStart Doc

python-pip package from canocnical for trusty is old.
It causes resolving dependencies problem when "pip install".

This fixes it.

Change-Id: I9134d9d46eba3e9c37167552bf90758690b62ecf
Closes-Bug: #1595792

coolsvap/kolla,intel-onp/kolla,openstack/kolla,dardelean/kolla-ansible,mandre/kolla,mandre/kolla,openstack/kolla,rahulunair/kolla,nihilifer/kolla,dardelean/kolla-ansible,rahulunair/kolla,coolsvap/kolla,stackforge/kolla,GalenMa/kolla,stackforge/kolla,mrangana/kolla,nihilifer/kolla,stackforge/kolla,coolsvap/kolla,intel-onp/kolla,dardelean/kolla-ansible,mandre/kolla,GalenMa/kolla,mrangana/kolla