Declare warn_about_rubies as a class method

Since that's how it's being called.  Also, define it before calling it.

lib/msf/core/db_manager.rb

@@ -20,16 +20,10 @@ module Msf
 ###
 
 class DBManager
-	begin
-		include MetasploitDataModels
-	rescue NameError => e
-		warn_about_rubies
-		raise e
-	end
 
 	# Mainly, it's Ruby 1.9.1 that cause a lot of problems now, along with Ruby 1.8.6.
 	# Ruby 1.8.7 actually seems okay, but why tempt fate? Let's say 1.9.3 and beyond.
-	def warn_about_rubies
+	def self.warn_about_rubies
 		if ::RUBY_VERSION =~ /^1\.9\.[012]($|[^\d])/
 			$stderr.puts "**************************************************************************************"
 			$stderr.puts "Metasploit requires at least Ruby 1.9.3. For an easy upgrade path, see https://rvm.io/"
@@ -37,6 +31,13 @@ class DBManager
 		end
 	end
 
+	begin
+		include MetasploitDataModels
+	rescue NameError => e
+		warn_about_rubies
+		raise e
+	end
+
 	# Provides :framework and other accessors
 	include Framework::Offspring