Fixes bug 497731 - Fixed list of possible values, removed all errors-related words.

Anyone r?

I realized while testing on stage that some of the default values for the ``exploitability`` field didn't make sense. I pulled them from elasticsearch and didn't see that they were just explanations of various errors. This removes those values and only keeps the ``error`` word. If a user wants to search for something more specific, that is still possible but not proposed by the UI.