Improve error messages displayed in graph error images

[zimmermatt]

Splitting out the suggestions from @svachalek and @nathfisher in Issue #19.

Scott's suggestion

Colors would be good, but some clear templating might be more important. Something along the lines of:

There was an internal error in the Atlas server, please report this message to the support team: [internal error message]

or

The load on the Atlas server is currently too high. Please wait a few minutes before resubmitting this query, or contact the support team for further assistance.

or

Query was invalid. Please correct the query and resubmit: [query error message]

or

Your query cannot be processed as written due to the size of the result set. Please consult the FAQ for suggested ways to reduce the size of the result set. [detailed error]

Nathan's suggestion

add some sort of code that could be used to lookup the error information.