* add types for custom ordering functions
* fix trailing whitespace
* include dependency on moment (2.13 being the first version to include types)
add type for moment constructor for use in timeline and graph2d options
* Updating template function defintion
As mentioned [here](https://github.com/seveves/ng2-vis/issues/32) there is a problem with the definition of the template functions. We really should allow any as a return value because you can return a string, Handlebars, mustache or even react templates. As you can see [here](http://visjs.org/docs/timeline/#Templates) the template function always has three parameters. I made them optional because you don't have to use them at all.
* Using fat arrow syntax
I think this is the right way to do it.
* Fix lint error
