Add search icon. Closes #22.
Add unique template joining all share methods.
Add recipe icon on mixture detail. Closes #23.
Add multiple icons in site.

* Add icon for mixture list in nav bar. Closes #26.
* Add contact icon. Closes #25.
* Add home icon in nav bar. Closes #24.
* Add icon for categories in nav bar. Closes #27.
Add home, mixture and category icons.