Fix capistrano#75 (static gemset release)

Thanks to @cgreigo. Gem release date will now be inferred by `rubygems.org`

capistrano.gemspec

@@ -11,7 +11,6 @@ Gem::Specification.new do |s|
   s.homepage    = "http://github.com/capistrano/capistrano"
   s.summary     = %q{Capistrano - Welcome to easy deployment with Ruby over SSH}
   s.description = %q{Capistrano is a utility and framework for executing commands in parallel on multiple remote machines, via SSH.}
-  s.date        = %q{2011-03-22}
   s.files         = `git ls-files`.split("\n")
   s.test_files    = `git ls-files -- {test,spec,features}/*`.split("\n")
   s.executables   = `git ls-files -- bin/*`.split("\n").map{ |f| File.basename(f) }