添加移动端分享功能

	modified:   app/assets/javascripts/mobile.js
	modified:   app/assets/stylesheets/mobile/questions_left.css.scss.erb
	modified:   app/views/mobile/answers/_solution.html.haml
	modified:   app/views/mobile/questions/_question.html.haml
	modified:   app/views/mobile/questions/_share.html.haml
	new file:   app/views/mobile/questions/_social_buttom_links.html.haml
	new file:   app/views/mobile/questions/_social_links.html.haml