bottles: new method bottle_resolve_vesrion

Library/Homebrew/bottles.rb

@@ -57,6 +57,10 @@ def bottle_resolve_formula_names bottle_file
   [name, full_name]
 end
 
+def bottle_resolve_version bottle_file
+  Version.new bottle_receipt_path(bottle_file).split("/")[1]
+end
+
 class Bintray
   def self.package(formula_name)
     formula_name.to_s.gsub "+", "x"