Add collectstatic commands to install doc

Added directions on how to run collectstatic and compress as part of the
install process.  Fixing obvious typos as well.

Change-Id: Ia51bb7bb644dc213b3ec3fd3866633700a73c7f9
Closes-Bug: 1392804
Merge "Add collectstatic commands to install doc"
Merge branch 'master' of https://github.com/openstack/horizon