[JSCodeHints] Should be able to configure require roots

[petetronic]

From njx: "It would be nice to have a way to configure module roots, possibly in a settings panel. For Brackets, I initially thought the module-based hinting wasn't working because I usually set my project root to be the root of the brackets repo. It all started working properly once I figured out to open the src folder."

[petetronic]

For the full discussion, see: adobe-research#32

[eztierney]

Updated the code to find files that end with module name, so now we should be able to find requirejs modules when the 'brackets' folder is the project root instead of the 'brackets/src' folder.
#3553

[dangoor]

Reviewed as part of reviewing code hinting issues. I think the priority of this is a bit lower now given the fix just described.

[njx]

Marking move to backlog. @pfarland - another one for you to consider.

[petetronic]

Moved to Brackets Research backlog https://trello.com/c/oUDKjh4M