Allow for simple branding of the webapp

We need some simple branding options for the webapp. for now, we can keep it real simple:

• ability to configure the site title (instead of 'Leap Web')
• ability to configure the favicon url
• ability to include a custom css snippet

all these can be configured via a simple initializer or config file that is generate by the puppet recipe.

(from redmine: created on 2013-01-10)