Improve input example message layout
Improve input example message layout

Setting 'bottom' in the layout of a ScrollView child is ambiguous. This
made the message text view detach from its top layout reference on
Android. Remove bottom layout definition and add a spacer composite
instead.

Don't recreate the message text view each time the message changes.
Update its 'text' property instead. This is easier to understand.

Change-Id: Id3d90850f81efe8b49ed61e085b29dbeb19900cf

eclipsesource/tabris-js,eclipsesource/tabris-js,eclipsesource/tabris-js