Hiding function implementation - the hide function is complete

Signed-off-by: Bogdan Purcareata <bogdan.purcareata@gmail.com>
Removed test binary since hide_message now has full implementation

Signed-off-by: Bogdan Purcareata <bogdan.purcareata@gmail.com>
Added reveal message initial stub function

Signed-off-by: Bogdan Purcareata <bogdan.purcareata@gmail.com>