Custom table header class using auto layout throws the assertion "Auto L...

Implementing a custom AMSlideTableHeader using throws the assertion "Auto Layout still required after executing -layoutSubviews" when using auto layout. Adding call to [super layoutSubviews] in AMSlideTableHeader solves this. Not sure if this has any impact on the default AMSlideTableHeader

Signed-off-by: Aniruddha Chitre <achitre@chenoainc.com>