Bug 887110 - [Clock] Fix clock face tick marks and hands to adhere to spec

- JS changes
    - Removed the angle offset for the clock hands since they now all start at 0 degrees
- HTML/CSS changes
    - Removed .png files for marks at 1, 1.5x, 2.0x
    - Inserted new analog clock face/hands divs (with SVG backgrounds) into clock's index.html
    - Positioned new hands to fit new clock face with CSS
    - Some format cleanup in `clock.css`
- Unit Tests
    - Updated the unit tests to test he clock hands against the new angles (not offset)
- Manual Tests
    - Tested new face in browser and on Unagi
    - Tested resizing by adding/removing alarms to cause the alarm list to grow/shrink and face to resize
- Issues
    - Wasn't sure how to test the removal of images for 1.5x and 2.0x scale devices
    - Found a new bug: clock doesn't resize to largest size when all alarms are deleted from a list, but that can maybe be taken care of with this bug later: https://bugzilla.mozilla.org/show_bug.cgi?id=910854
    - `clock.css` file was not refactored in its entirety, perhaps for a later bug?