Add contact form into home and mixture detail. Closes #13.

* Fix home titles and links.
* Add custom CSS for home page.
* Add buttons and titles into home.
* Add django-contact-form to base requirements.
* Add contact form.
* Remove unused setting.
* Add django-contact-form URL conf.
* Add contact form links.
* Add contact form in home and mixture detail.
* Move environment settings into base.
* Add pending template formats for contact_form.
* Add logger configuration and default email settings.