Fix OptInt's valid?() function

[FixRM rapid7#7539] - The valid?() function will first normalize() the
user-supplied input before validation.  The problem is that the
normalize() function will ALWAYS convert data to integer, therefore
whatever you validate, you will always get true.  For example:
when I do "yomama".to_i, that returns 0, and of course will pass
integer validation.

Author: sinn3r

lib/msf/core/option_container.rb

@@ -441,7 +441,7 @@ def normalize(value)
 	def valid?(value)
 		return false if empty_required_value?(value)
 
-		if value and not normalize(value).to_s.match(/^\d+$/)
+		if value and not value.to_s.match(/^\d+$/)
 			return false
 		end