User Guide: document the manual creation of openrc.sh

This helps if the user doesn't have access to an OpenStack dashboard.

Change-Id: I2e9e86e2bf092a0b429c2c4da32618d7e7b1078f
backport: none
Ensure all "os" values are valid/recognized

Added a check to ensure that all "os" values are valid/recognized. The
list of recognized values is contained in a global and can be updated
if/when we add any further operating systems.

Note that "adminuser" and "enduser" values are also included as
recognized as they are required by the user guides at this time.

Change-Id: I3303b9cb880b70cbf8298eecafc56dffe2276476
Add admin guide for the l3 metering extensions

Partial-bug: #1202967
Change-Id: Ic55def1550afc55b1bda87e74602006fcf27adf9
Install guide: rework the ceilometer section

* misc editing details (spacing, formatting, capitalization, replaceable
  data)
* give configuration file examples where possible
* reduce the delta between distributions to make things more easily
  maintainable (and possibly clearer)

Change-Id: I2a8b3df1d26cb052c3ed71dc706f1243d1f0391f
backport: havana
Install Guide: document how to test the ceilometer installation

Change-Id: I4b5ea1f198f20083dc887d589e2d0b6a7f9116ba
backport: havana
Install Guide: Fix wrong service referenced

We need to configure ceilometer.conf like it's shown correctly for
Debian a few lines later.

Change-Id: I36b12a263cdd2d6978c3cc3c35556bf59ce83ce7
Closes-Bug: #1252273
backport: havana
Install Guide: Fix profiling information

This screen was erroneously shown on Ubuntu, fix profiling.

Change-Id: Id908acfdc739ad8873263f21897a1fcccee2bf60
backport: havana
Closes-Bug: #1252316
Merge "Install Guide: Fix wrong service referenced"
Merge "Add admin guide for the l3 metering extensions"
Merge "Install guide: rework the ceilometer section"
Merge "Install Guide: document how to test the ceilometer installation"
Merge "Ensure all "os" values are valid/recognized"
Merge "User Guide: document the manual creation of openrc.sh"