Namespace cleanup

The primary fix for this PR is a namespace change for the global methods. I have moved the global methods from `datePicker.js` into `datePickerUtils.js`, the methods are now defined in a factory which can be injected where they are needed. Some of the methods that reference other methods needed changes e.g. `isSameMonth`

Additional changes:
* added tests for datePickerUtils methods - some of the tests are a bit basic.
* added intellij .iml files to gitignore
* updated the index.html to use the `angular.js` from `angular.min.js` to make debugging easier as it provides meaningful error messages.