Add new icons to menus and toolbar

- added new icons to menus and toolbar
Merge branch 'dev' into feature/new-icons

Conflicts:
	app/assets/stylesheets/fonts/_openproject_icon_font.sass
	public/templates/work_packages.html
	public/templates/work_packages/column_context_menu.html
Showing/hiding display sums icon.
Merge branch 'dev' into feature/new-icons

Conflicts:
	public/templates/work_packages.html
align menu items without icon

should be replaced by icon later
Merge pull request #1370 from opf/feature/new-icons

Add new icons to menus and toolbar