Remember files that timed out in Tern

This is a squashed version of PR https://github.com/adobe/brackets/pull/8198. See for more comments.

This is to finish Trello Card: https://trello.com/c/2ra9FzGL/1284-m-js-code-hints-automatic-crash-preventer
Yes, it would be nice for user to be able to edit in UI, but I think it introduces a whole new concept of an exclusion list that is only shown for editing. As I tried to state earlier, the detectedExclusions list is *always* checked (so user cannot select or unselect this exclusion list) and any other user exclusion list is also checked.

I don't think it's worth trying to update UI for this special case. I think we should merge this PR as is (i.e. require user to manually edit prefs).

One other idea I had is to automatically remove any file being edited from detectedExclusions list. Presumably user is editing file to *fix* it, and if it fails again, it will be re-added to detectedExclusions list. While this sounds slick, it may be tricky to get this just right. But this doesn't handle case of a problematic file being updated outside of Brackets.