Add glance configuration reference tables

This is the first attempt at automatically generated configuration
tables being added to documentation.
blueprints.launchpad.net/openstack-manuals/+spec/autogenerate-config-tables">https://blueprints.launchpad.net/openstack-manuals/+spec/autogenerate-config-tables
Blueprint-autogenerate-config-tables">https://wiki.openstack.org/wiki/Blueprint-autogenerate-config-tables

Work is being conducted out-of-repo at :

https://github.com/fifieldt/autogenerate-config-docs

Glance previously did not have such tables, but submitting these for
review without linking them in to a book yet, because feedback is needed.

Please provide feedback on:
* completeness (is every option and its description present)
* groupings (is every option in the right group)
* potential integrations (can you see where one or more of these
tables could be combined under a nice descriptive paragraph)
* relationships to config files (are these useful as is, or how to
best integrate them with examples)
* anything else you can think of

patchset 2 fixes spacing with header text and XML escapes
the description strings

patchset 3 links the tables into the compute admin guide

fixes bug 1077555
fixes bug 1156109

Change-Id: I01e05dcf2178adfdb75d8559b107b1c2ba0c7060
Merge "Add glance configuration reference tables"