Fix gem version to support rubygems < 2.1

MSP-10714

lib/metasploit/framework/version.rb

@@ -8,5 +8,6 @@ module Metasploit
     end
 
     VERSION = "#{Version::MAJOR}.#{Version::MINOR}.#{Version::PATCH}-#{Version::PRERELEASE}"
+    GEM_VERSION = "#{Version::MAJOR}.#{Version::MINOR}.#{Version::PATCH}.#{Version::PRERELEASE.gsub(/[^0-9a-zA-Z]/, '')}"
   end
 end

metasploit-framework.gemspec

@@ -7,7 +7,7 @@ require 'metasploit/framework/version'
 
 Gem::Specification.new do |spec|
   spec.name          = 'metasploit-framework'
-  spec.version       = Metasploit::Framework::VERSION
+  spec.version       = Metasploit::Framework::GEM_VERSION
   spec.authors       = ['Metasploit Hackers']
   spec.email         = ['metasploit-hackers@lists.sourceforge.net']
   spec.summary       = 'metasploit-framework'