Cleanup

Added grunt config and dependencies in package.json. To jshint and produce uglifyjs minified ios-drag-drop.min.js use:
```
npm install -g grunt-cli
npm install
grunt
```
To satisfy jshint I converted double quotes to single, added {} around if clauses and added/removed semilcolons.

There are some warnings remaining due to var missing on some variable declarations. Will send another pull request for those if this is ok.

jshint ios-drag-drop.js returns
```
ios-drag-drop.js: line 3, col 5, Missing "use strict" statement.
ios-drag-drop.js: line 10, col 47, 'navigator' is not defined.
ios-drag-drop.js: line 13, col 9, 'dragDiv' is not defined.
ios-drag-drop.js: line 14, col 9, 'evts' is not defined.
ios-drag-drop.js: line 16, col 28, 'dragDiv' is not defined.
ios-drag-drop.js: line 16, col 39, 'evts' is not defined.
ios-drag-drop.js: line 16, col 72, 'navigator' is not defined.
ios-drag-drop.js: line 129, col 13, 'target' is not defined.
ios-drag-drop.js: line 171, col 9, 'target' is not defined.
ios-drag-drop.js: line 182, col 16, 'target' is not defined.

10 errors
```