Fix framework before check

The framework would ignore the `before` function if the command was not
ran by an owner. Instead, flip the conditions so that it's always run,
and then the result is succeeded by an owner check.

src/ext/framework/mod.rs

@@ -503,7 +503,7 @@ impl Framework {
 
                         thread::spawn(move || {
                             if let Some(before) = before {
-                                if !is_owner && !(before)(&context, &message, &built) {
+                                if !(before)(&context, &message, &built) && !is_owner {
                                     return;
                                 }
                             }