Gemspec: drop EOL'd property rubyforge_project (#477)

Gemspec: drop EOL'd property rubyforge_project

Author: jonnyom

intercom.gemspec

@@ -12,7 +12,6 @@ Gem::Specification.new do |spec|
   spec.summary     = %q{Ruby bindings for the Intercom API}
   spec.description = %Q{Intercom (https://www.intercom.io) is a customer relationship management and messaging tool for web app owners. This library wraps the api provided by Intercom. See http://docs.intercom.io/api for more details. }
   spec.license     = "MIT"
-  spec.rubyforge_project = "intercom"
 
   spec.files         = `git ls-files`.split("\n")
   spec.test_files    = `git ls-files -- {test,spec,features}/*`.split("\n")