Avoid LoadError when using rake (#77)

Previously it wasn't even possible to list the rake tasks, because this
`rails/tasks/statistics.rake` file does not exist.

It was added in a very large initial commit [1] which doesn't mention
it in the commit note, so I have no idea what its origins are.

[1]:
79600c9

Author: floehopper

Rakefile

@@ -2,6 +2,4 @@
 
 require 'bundler/setup'
 
-load 'rails/tasks/statistics.rake'
-
 require 'bundler/gem_tasks'