Be explicit about Toast context

Fixes jdamcd#113

Author: jdamcd

lib/src/main/java/com/soundcloud/android/crop/Crop.java

@@ -250,7 +250,7 @@ private static Intent getImagePicker() {
     }
 
     private static void showImagePickerError(Context context) {
-        Toast.makeText(context, R.string.crop__pick_error, Toast.LENGTH_SHORT).show();
+        Toast.makeText(context.getApplicationContext(), R.string.crop__pick_error, Toast.LENGTH_SHORT).show();
     }
 
 }