chrislloyd/gravtastic — pull request #33 by unreal (2013-02-05 17:46:52+00:00)
Title: Allow options to be set with a proc/lambda

I needed to be able to set the default gravatar image based on the actual object instance.

example:

```ruby
class User
# default image is the first letter of the user's first name
gravtastic default: lambda { |u| "http://assets.example.com/#{u.first_name[0]}.jpg