Update documentation surrounding the api and registry servers

Change-Id: I24e288eae841190e0776623b29da0bf8b9b9d34c
Changing Sheepdog driver to use correct configuration function

Currently Sheepdog store driver is using configure_add() to handle
those essential options, which are not only be used for image 'add'
handling but also for other key functions e.g. 'get_size', 'get' and
etc. When store driver raises BadStoreConfiguration exception from
configure_add(), Glance will just makes this store be readonly instead
of fully disabled, so the handling for all the essential configurations
should be implemented in configure(), and then if any option of them get
failure the store will be fully disabled instead of being readonly
partially.

Closes-bug: 1302658

Change-Id: Idaa96036515f04ee8414f30990ee638855ede2d2
Signed-off-by: Zhi Yan Liu <zhiyanl@cn.ibm.com>
Added an extra parameter to the df command

The parameter is needed to avoid multi-line output,
which results in an IndexError,
because only one line is being searched for values.

Change-Id: Ie518c6a3573b7868065501a02cd0bd8565656a71
Closes-Bug: 1336238
Fix docstrings in enforce() and check() policy methods

Proper name of the  parameter is 'target', not 'object'.

Change-Id: Ia7a671c9aed644137e4c46452d8d8bf3bc3f2eee
Merge "Update documentation surrounding the api and registry servers"
Merge "Added an extra parameter to the df command"
Merge "Changing Sheepdog driver to use correct configuration function"
Some v2 exceptions raise unicodeError

Use utils.exception_to_str to consistently cast the
excpetion to avoid the unicodeError stack trace.

Change-Id: I54fce91c73adca846ec99ed50a57b95d16428ec1
Closes-Bug: #1339775
Merge "Fix docstrings in enforce() and check() policy methods"
Merge "Some v2 exceptions raise unicodeError"