Various lint error fixes.

> Fixing some RTL errors by specifying both marginStart and marginLeft
> Moving all layout direction checks to Utilities
> Explicitely adding @TargetApi before every method

Change-Id: Ibe9c52b93b5a6adeadb27ace2b312770fd732ea0
diff --git a/src/com/android/launcher3/DragView.java b/src/com/android/launcher3/DragView.java
index 3eec3d9..120299e 100644
--- a/src/com/android/launcher3/DragView.java
+++ b/src/com/android/launcher3/DragView.java
@@ -76,6 +76,7 @@
      * @param registrationX The x coordinate of the registration point.
      * @param registrationY The y coordinate of the registration point.
      */
+    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
     public DragView(Launcher launcher, Bitmap bitmap, int registrationX, int registrationY,
             int left, int top, int width, int height, final float initialScale) {
         super(launcher);