Prevent the custom View to be drawn in the UI editor

Usually the UI editor in Eclipse or IntelliJ will throw errors, if they are trying to render complex custom Views. These two lines will prevent that.
updated build.gradle, AndroidManifest.xml, DemoActivity, SlidingUpPanelLayout
Merge pull request #162 from Rashiq/master

Prevent the custom View to be drawn in the UI editor
Merge pull request #163 from ousenko/fff

updated build.gradle, AndroidManifest.xml, DemoActivity, SlidingUpPanelL...
Update SlidingUpPanelLayout.java

Fix "might not be initialized" error for final fields
Update SlidingUpPanelLayout.java

Fix "might not be initialized" error for final fields
Merge pull request #165 from lsycxyj/patch-1

Update SlidingUpPanelLayout.java