renamed index files of two guides

Use bk_ instead of bk- to match the name of all other documents.

Use openstack-install-guide instead of openstackinstallguide.

Change-Id: I819774a726a3ac50bf0e9a82a03a53a6ae8c674c
Fixes 'Wrong description for installing command-line clients'

The information about installing python-novaclient in the
'how to install pip' section is now removed.

Change-Id: I4570be4cfd18ec7fef86fa6ffa1d38d9442571c9
Closes-Bug: #1324912
Merge "renamed index files of two guides"
Merge "Fixes 'Wrong description for installing command-line clients'"