Add audit details page and audit tracing

[mrferris]

This PR adds a string column to the contentaudit schema, and renders the query graph on the audit details page for audits that have traces.

todo:

• Add query stats to audit details page
• Add table view of nodes next to graph view
• Get rid of 13k line diff to bootstrap.min.css

[mrferris]

@pipermerriam When you have a second mind quickly reviewing this? The DB migration is the main thing that will affect anything else.

I've updated this to not call the Trace endpoint, so trace columns in the DB will be empty and things will looks the same.

Once we merge #110 we'll know on the fly whether a given client supports the Trace endpoint and if so we'll populate the trace field and the functionality in this PR will link & display the query's trace.

[pipermerriam]

👍