Re-enable compatibility with Brackets versions >=0.20.0

[jasonsanjose]

I intentionally broke compatibility with Brackets via the package.json engine property. It's now limited to <0.20.0 (before the CodeMirror v3 upgrade).

Once issue #44 and related issues are resolved we should update this compatibility.

[genericandy]

Hi - I really liked this extension & it looks like issue 44 is well & resolved. Are you going to continue to update this extension as I found it really helpful.

[jdiehl]

It has been a while, since I have worked on this extension... I'll take a look at it and see how easy it is to adapt to the latest Brackets version.

[genericandy]

It seems to be working except for one odd bug. (I manually added it to the active folder). After a Live Preview is opened a notice pops up "Live Preview Error: Unable to load live preview page". But even after closing the notice, the live preview and your console work.