Add the state of the experiment to experiments list

It is hard to tell which tests are running and which are not, so I
suggest adding a color to the left on the experiments list. Red is for
stopped and green is for running. Colors used are from the [Firefox OS
guide](http://buildingfirefoxos.com/common-controls/fonts-and-colors/)
Color a little dot instead of the full cell
Merge pull request #11 from smgt/add-active-marker-on-experiments

Add the state of the experiment to experiments list