Fixed some Expression and Operand memory issues.

Global.cpp

@@ -90,7 +90,7 @@ namespace jet {
 
    void Global::outputHeaders() {
       if(headers.size() > 0) {	
-	 for(std::map<coreutils::MString, coreutils::MString>::iterator header = headers.begin();
+	 for(auto header = headers.begin();
 	     header != headers.end();
 	     ++header) {
 	    std::cout << header->first << ": " << header->second << std::endl;