Dynamic animations

Removed:
- rFrames, fFrames from buttons.js
- ROTATIONFRAMES, ROTATIONDROPOFF, FLIPPINGFRAMES, FLIPPINGDROPOFF from
common.js

Added
- calcSpeed() helper to determining the time it takes to render a frame
- testFrameRate() to calculate the number of frames needed per device.
Called in main.js before page load occurs
- numFrames, the total number of frames need for the device.  Replaces
fFrames and rFrames in buttons.js

Note: The algorithm for calculating the frame rate still needs to be
optimized.  It currently works, but not to the required effectiveness.
Merge pull request #8 from pfryerda/time_based_animations

Dynamic animations