atop: add recipe

Add recipe for atop.

* remove bashisms for scripts
* fix permissions for executable files
* create volatile directory /var/volatile/log/atop
* implement status command in sysvinit script
* drop atopacctd which is excluded from most distribution such as Ubuntu
  and Fedora

Signed-off-by: Kai Kang <kai.kang@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>