C BUTTON NOW CHANGED VALUE TO 0 BUT ALLOWS UNDO, AV FUNCTION NOW PRESENT

- c button changes value to zero and allows undo
- if current display value is zero the c button changes to AC
- AC completely clears values, undo not allowed
Merge branch 'master' of https://github.com/sparkrevolutions/arithmetick2

# By Matthew Mcclatchie
# Via Matthew Mcclatchie
* 'master' of https://github.com/sparkrevolutions/arithmetick2:
  UI ADJUSTMENTS

Conflicts:
	cordova/platforms/ios/www/javascripts/app.js.map
	cordova/platforms/ios/www/stylesheets/app.css
	cordova/platforms/ios/www/stylesheets/app.css.map
	cordova/platforms/ios/www/test/javascripts/tests.js.map
	cordova/www/javascripts/app.js.map
	cordova/www/stylesheets/app.css
	cordova/www/stylesheets/app.css.map
	cordova/www/test/javascripts/tests.js.map