Fix rdoc/rake deprecation warning
Fix rdoc/rake deprecation warning

WARNING: 'require 'rake/rdoctask'' is deprecated.  Please use 'require 'rdoc/task' (in RDoc 2.4.2+)' instead.
    at /home/avsej/.rvm/gems/ruby-1.9.3-p194@global/gems/rake-0.9.2.2/lib/rake/rdoctask.rb

Mahaswami/netzke-core,citrininfo/netzke-core,Mahaswami/netzke-core,Mahaswami/netzke-core,citrininfo/netzke-core,citrininfo/netzke-core,citrininfo/netzke-core