fix: resolveOrientation function not working correctly (#77)

Fixing a problem that was making the screen not to be locked as described on https://www.outsystems.com/forums/discussion/67761/resolveorientation-bug/
diff --git a/www/screenorientation.js b/www/screenorientation.js
index d8fe529..4e98e9a 100644
--- a/www/screenorientation.js
+++ b/www/screenorientation.js
@@ -84,7 +84,7 @@
 }
 
 function resolveOrientation (orientation, resolve, reject) {
-    if (!Object.prototype.hasOwnProperty.call(OrientationLockType, 'orientation')) {
+    if (!Object.prototype.hasOwnProperty.call(OrientationLockType, orientation)) {
         var err = new Error();
         err.name = 'NotSupportedError';
         reject(err); // "cannot change orientation");