Update package.json to set jquery dep as peer dependency

I'm having some issues of duplicated jQuery instances when using jQuery contextMenu with npm 3.x. This works great when jQuery is declared as a peer dependency (and this is the recommended declaration of dependencies for plugins).

Author: fredericlb

package.json

@@ -7,7 +7,7 @@
     "url": "http://www.swis.nl"
   },
   "license": "MIT",
-  "dependencies": {
+  "peerDependencies": {
     "jquery": "^1.8.2"
   },
   "devDependencies": {