Updating consumer content docs.
Fixing a minor bug in schedule retrieval that revealed too much data to the API user.

I consolidated the content schedule docs so that instead of listing the same
exhaustive set of docs for each action (install, update, uninstall), we list
the exhaustive docs once and specify that any of the three actions can be used.
Merge pull request #769 from pulp/mhrivnak-sched-docs

Updating consumer content docs.