Moved jQuery to peer dependency

[shovon]

If Gridster relies on its own version of jQuery, then we are faced with two problems

• if the parent module also relies on jQuery, then the final Browserify/Webpack build will embed two different versions of jQuery
• we will have two JavaScript (pointer) references to jQuery. This means that there are cases where initializing a jQuery object in one source file will yield an entirely different instance when initializing from another, e.g. in file 1, we do var foo = $('css selector'), and in file two, we refer to foo somehow, and yet, running foo instanceof jQuery will be false. I'm oversimplifying the problem, but I did come across the exact same issue because a child module was not a peer dependency.

[shovon]

Depending on how you manage semver versions, you may also want to bump up the version defined in package.json.