Project permissions capabilities

Added show-repo-account-access command
added show-account-access command
Cleaned up documentation for show-account command
reformatted some code to better meet Gerrit's standards
Tweaked error handling, switched to @RequiresCapability
to ensure calling user is an Administrator

Change-Id: I5c1e53ddeebea18f2ee9d04b9d25d964dbb1ee6d