Add ability to change header color for SlidingUpActivities.
Add mixing colors method and apply to SlidingUp examples.
Improve and add more functions to SlidingUp examples. #32
Extract a method to change title visibility on SlidingUp examples.
Fix toolbar title visibility becomes wrong when sliding up and down fast in SlidingUp examples. #32
Merge https://github.com/ksoichiro/Android-ObservableScrollView

Signed-off-by: Andrea Cappelli <a.cappelli87@gmail.com>

Conflicts:
	observablescrollview-samples/src/main/java/com/github/ksoichiro/android/observablescrollview/samples/SlidingUpBaseActivity.java
	observablescrollview-samples/src/main/res/layout/activity_slidingupscrollview.xml