releasing 1.5.0

CHANGELOG.rdoc

-1.5.0 (not yet released)
+1.5.0 (January 11, 2011)
 
 * Added an Ability generator - see issue #170
 

cancan.gemspec

 Gem::Specification.new do |s|
   s.name        = "cancan"
-  s.version     = "1.5.0.beta1"
+  s.version     = "1.5.0"
   s.author      = "Ryan Bates"
   s.email       = "ryan@railscasts.com"
   s.homepage    = "http://github.com/ryanb/cancan"