As zabbix agentd cannot run in foreground mode wrap it in simple foreground
application which sends singals whenever it is requested to be killed.

Instantiation shall depend on minimal tools, like system administrator would.

The master branch should contains always stable code, so it is required
to define stable version numbers for everything.

This reverts commit 5c763b0089dbdf355c0efe8830e808e9580735f6.
We keep slapos.recipe.download in slapos.cookbook