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/DeviceProfile.java b/src/com/android/launcher3/DeviceProfile.java
index 890b9c9..33c3d50 100644
--- a/src/com/android/launcher3/DeviceProfile.java
+++ b/src/com/android/launcher3/DeviceProfile.java
@@ -459,11 +459,7 @@
         isLandscape = (configuration.orientation == Configuration.ORIENTATION_LANDSCAPE);
         isTablet = resources.getBoolean(R.bool.is_tablet);
         isLargeTablet = resources.getBoolean(R.bool.is_large_tablet);
-        if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.JELLY_BEAN_MR1) {
-            isLayoutRtl = (configuration.getLayoutDirection() == View.LAYOUT_DIRECTION_RTL);
-        } else {
-            isLayoutRtl = false;
-        }
+        isLayoutRtl = Utilities.isRtl(resources);
         widthPx = wPx;
         heightPx = hPx;
         availableWidthPx = awPx;