Quick initial integration of software keyboard into KA Lite exercises.
Merge branch 'css_cleanup' into software-keyboard
Tweaks to styling for software keyboard.
Adding other mather notations.
Adding clear input field function.
Fixed "next question" displaying issue
Showing Numberpad
Only show the numberpad if it is an andriod device.
Fix some formats
Signed-off-by: wangguan59 <wangguan59@gmail.com>
Merge branch 'develop' into software-keyboard
Show up on all the devices.
Fix for #356

Usernames are truncated if longer than max-width.
Using vw instead of em in caption sizes

vw allows for more responsive text design because it changes the font-size based on the size of the viewport. (1vw = 1% viewport width.)
Using vw instead of em in caption sizes

vw allows for more responsive text design because it changes the font-size based on the size of the viewport. (1vw = 1% viewport width.)
Fix for overflowing buttons in Update Videos page

This > https://i.imgur.com/NrJ28jA.png
Quick initial integration of software keyboard into KA Lite exercises.

Conflicts:
	kalite/distributed/templates/distributed/exercise.html
	kalite/static/js/khan-exercises/khan-exercise.js
	kalite/static/js/khan-exercises/utils/answer-types.js
Moves software-keyboard to new location.
Implements first pass of Backbone driven software keyboard.

Conflicts:
	kalite/distributed/static/css/distributed/khan-lite.css
Makes numpad appear for all applicable answer types.