Updated backup-restore howto

Updated backup-restore howto to reflect current state of
the process for HA
Merge branch 'master' of https://github.com/juju/docs
Added high availability docs

Added the ensure-availability command to the commands list
Added a brief howto on how to use ensure-availability
Add Note about using .pem instead of a .cer.
Merge pull request #121 from castrojo/azure-cert

Add Note about using .pem instead of a .cer.
Delete debug-log caveat from local-provider docs

The bug was fixed a while ago; debug-log now works
uniformly across all providers.
Merge pull request #122 from axw/config-lxc-delete-caveats

Delete debug-log caveat from local-provider docs
added metadata
Add Charm Helpers page with link to docs
Merge pull request #125 from tvansteenburgh/charm-helpers

Add Charm Helpers page with link to docs
Update 'charm create' docs with new template stuff
Add section for create options
Merge pull request #126 from tvansteenburgh/charm-create-templates

Update 'charm create' docs with new template stuff
Merge pull request #112 from perrito666/add_HA_howto

Added high availability docs
Merge pull request #107 from perrito666/master

Updated backup-restore howto
/Using charms/Using Juju
Added debug-log documentation.
Switch contraints reference to list format because the conversion of definition list to markdown created bogus code examples.
Add High Availability page.
Add actual HA docs.