Bug 1080408 - Adjust wording for 'Unknown revision ID' page

This work fixes Bugzilla bug [1080408](https://bugzilla.mozilla.org/show_bug.cgi?id=1080408).

This updates the unknown revision ID message, as requested by Ed.

Here is a screen grab of the fix (minus the unknown revision which would precede the spinner).

![unknownrevidmsg](https://cloud.githubusercontent.com/assets/3660661/4652746/9e8f08f6-54a7-11e4-8532-b0cc166f6440.jpg)

I added a div to open up a full line for the revision, for clarity. A couple of minor word tweaks, and I tidied up the code block wrap. In doing so it seemed to make sense to make the adjacent code blocks for *No resultset* and *Unknown repository* to the same indent style for `ng-show`. let me know if I've missed something in that indent style. It seems easier to read anyway.

I left the text as 2-space indent to its parent tag, the same as the others.

The spinner is supported on Firefox only, but I had a look at the behavior on Chrome and it seems fine.

Tested on Windows:
FF Release **32.0.3**
Chrome Latest Release **37.0.2062.124 m**

Adding @camd for review and @edmorley for visibility.