GH Examples Working, Api doc, Event Example

Note: There are a lot of files in this but only one change to cedar itself. The others are doc / example / dev artifacts proving out how things can work.

Fixed js and json pathing so examples work at http://esridc.github.io/cedar/

Added example to explore eventing http://esridc.github.io/cedar/examples/scatter-events.html
- currently using the native vega events 

Initial API docs http://esridc.github.io/cedar/api-reference/
- require formatting / styling

Changed "generateChart" method to "compile" - open to ideas on naming this method. http://esridc.github.io/cedar/api-reference/compile.html
Mapstraction solves this by testing if the library `isLoaded` and if it's not it builds an array of deferred methods that are run once the object has finished instantiating. See [runDeferred](https://github.com/mapstraction/mxn/blob/master/source/mxn.core.js#L461-L472)

To start for now, we could still wrap this up like so: 

```json
Cedar.create("/path/to/bar.json", {url: "FeatureServer/0", mappings: {count: "TOTAL_STUDENTS", group: "FACUSE"}, function(chart) {
 chart.show("#students-div");
});
```

which works just as well if the Style object is sent inline

```json
Cedar.create({inputs: "...", marks: "..."}, {url: "FeatureServer/0", mappings: {count: "TOTAL_STUDENTS", group: "FACUSE"}, function(chart) {
 chart.show("#students-div");
});
```