Add SAIO fix for Ubuntu 12.04

The version of setup tools in Ubuntu 12.04 is too old and is causing
the SAIO instructions to fail when installing python-swiftclient.

The work around is to install python-swiftclient's dependencies
before running running:

  python setup.py develop

This change adds a note to users of Ubuntu 12.04 to replace step 2
of "Getting the code" with:

  cd $HOME/python-swiftclient; sudo pip install -r requirements.txt; \
                               python setup.py develop; cd -

Change-Id: I63f57bbf1f1158f8740f6137ad55ff49f12a316c
Closes-Bug: #1217288
Merge "Add SAIO fix for Ubuntu 12.04"