Minor fixes for the nova section (install guide)

- Spacing/formatting updates
- Set the rpc_backend value to 'rabbit' for debian/ubuntu. This probably
  needs to be done for SUSE/RHEL ('rabbit' or 'qpid') but needs to be
  validated first.
- Simplify some examples
- On Ubuntu, remove the sqlite database before restarting the services

Change-Id: I0469e07d657ccd6a183caedf37cb0219d896be56
Update default rate limits for nova

Update limits to current limits in nova/api/openstack/compute/limits.py.
Remove sentence that dos not apply anymore.

Change-Id: Ib67c25731871a29eae38caa99af38ac2dd341a73
Closes-Bug: #1299907
Clarify description of neutron subnet-create

Better explain the parameter of the neutron subnet-create command.

Change-Id: Ice519027ebeebbc343a10546748350fc6ed731ae
Closes-Bug: #1299833
Moved security hardening HowTos from Config Ref to Cloud Admin

Moved procedures and theory over to the admin guide.
Also moved node recovery into its own file.
Edited trusted-flavor procedure with minor edits on rest.

Change-Id: I060d79271130d49b9c6b37638943e2f85ffae5cd
Partial-Bug: #290687
Added info on Guru Meditation reports for Compute

New section under Troubleshooting.
Related dev change is: I224a426dad084f0e738069207ffbffe7f7935a17

Closes-Bug: #1303253

Change-Id: I74c70289eb57c805ed0c582572802d39425f6964
Merge "Moved security hardening HowTos from Config Ref to Cloud Admin"
Merge "Update default rate limits for nova"
Merge "Minor fixes for the nova section (install guide)"
Removed HowTo quota procedures from Config Reference

The exact same section with procedures and descriptive table (not options) is already in the Admin User Guide.

Partial-Bug: #1290687

Change-Id: I422baa089da8df94b19d272ce8f0d47e4afec53e
Merge "Clarify description of neutron subnet-create"
Merge "Added info on Guru Meditation reports for Compute"
Merge "Removed HowTo quota procedures from Config Reference"