feat(splitView): expose side menu on large viewport

Ability to keep a left menu exposed on larger viewports, such as a
landscape tablet. Added the `expose-aside-menu` attribute directive.
feat($ionicBody): service to simplify body ele interaction

Many services/directives have to interact with the body element, and
each one has to write the same long code. The $ionicBody service
provides some useful methods to clean up and reduce redundant code.
style(z-index): order from small to larger
$ionicClickBlock reuse same element