Address comment feedback from #113

[shankari]

I am merging #113 to give @juemura and me a chance to play with the dashboard and suggest other changes as well. This issue is tracking the cleanup/comment feedback from #113.

The high level feedback is:

• Since we are always going to display the comparison with the last week unless it is a custom range, we can always get data for the past two weeks instead of making 2 calls to the server. You would do this by getting data from day(-1) to day(-14), grouped WEEKLY.
• we should avoid document.getElementById since it is not very angular-like. The angular way to do it is to use a directive. Alternatively, you can use something that what @krisma used to expand the control for the developer zone
• avoid string manipulation in the footprint. Not clear to me why it is required. No point in introducing fragility where it is not required.
• deletion of getOptimalFootprintDistance and getWorstFootprintDistance is making me nervous. Can you explain why they are no longer required?

[shankari]

also, there are a bunch of nits in the pull request (#113) which you can fix at the same time