v1.2.0 backend and watchapp improvements.

Change overview:
 * Support for Mars Time display with realtime LMST of MSL Curiosity Rover accurate to 10 seconds.
 * Manifest is now saved in JS Local storage so images are now viewable when phone has no internet connection.
 * Configuration page to show/hide mars time and select which instruments to show images from.
 * retriever.py downloads images in parallel, 10 at a time.
 * uploader.py only uploads the manifest.json and update_rdf.json
 * update_rdf.json used to reduce GET requests to manifest.json, update is checked every hour.

Additional actions needed for official deployment.
 1. Change the BUCKET_NAME in uploader.py
 2. Change DEFAULT_UPDATE_URL in watchapp/src/js/pebble-js-app.js (requires watchapp rebuild)
 3. Create ~/.boto config file with AWS info on ec2 instance.
 4. Upload watchapp/configurable.html to S3 bucket.

Watchface with Mars Time:

![photo 2](https://f.cloud.github.com/assets/323725/1865324/d2953a86-780b-11e3-8918-2ca73c73fc0f.jpeg)

New config screen:

![photo 1](https://f.cloud.github.com/assets/323725/1865318/8546fb34-780b-11e3-9aaa-6f56925e91cf.png)