Allow uploaded files to have embedded nulls

Minor bugfix that correctly passes uploaded files to the lua runtime
when they have embedded nulls.

src/libkore.c

@@ -251,7 +251,7 @@ lhttp_file_get(lua_State *L){
 		lua_error(L);
 	}
 	s[f->length] = '\0';
-	lua_pushstring(L,s);
+	lua_pushlstring(L,s,read);
 	return 1;
 }