Better spec code
Improved Mongoid::Giza::Index#field documentation
Added Mongoid::Giza::Index#criteria documentation
Method to remove selected generated indexes from the configuration
Use array instead of splat on Mongoid::Giza::Configuration#remove_generated_indexes
Mthod to remove all generated indexes of the model from the configuration
Fixed documentation for Mongoid::Giza::Configuration#remove_generated_indexes