Changed button colors and removed unused code.
Updated toolbar style; added mixins to enable easier theme
customization.
Updated button ui and style.
Changed confirm msgbox button ui to "action".
Updated scss/css declaration style; added button changes for speaker
view.
Updated style across all views;

Merge branch 'master' of git@scm.thm.de:arsnova/arsnova-mobile.git

Conflicts:
	src/main/webapp/app/view/speaker/form/ImageUploadPanel.js