[Review] Integrate Highcharts

Add [Highstock.js](http://www.highcharts.com/stock/demo) so that the user has greater control over graphs.

### To-do

- [x] Refactor
- [x] Allow user to input path to JMeter log file.
- [x] Integrate Highstock.js
- [x] Change to one-page.
- [x] Update README

![image.gif](http://fat.gfycat.com/EnormousSkinnyAnemonecrab.gif)