Old version of slap library are not using state parameter, so prove that new
version of Slap Tool is capable to speak with them.

Do not try to request start not fully installed computer partition, and wait
until instance setup packing list is stopped, before trying to create hosting
one.

Beside of setting state on Software instance by start/stop requested methods
setup in activities real request. Thanks to this *after* computer partition is
installed (instance setup packing list == stopped) the request becomes
synchronous (...a bit later -- in sense -- just once called).

It shall check for instance hosting, not instance setup.

Setup all required parameters before requesting again.

If internal bootstrap is used there is no need to clutter arguments with not
required command.

Play usual started scenario, and later after it is started, change the decision
and request it stopped.

Also fix docstring.

This was not implemented, and I overlooked it when implementing
-d/--dry-run option for some reason.

It is required in order to pass values like None.

Keep backward compatibility and start automatically just after partition become
available.

Implement start_requested and stop_requested states in order to have stateful
information about software instance requested state.

Asynchronously read software instance state and take proper actions in such
case (only after .available() call for now).

Note: Done in one big commit, as changes are interrelated, and impact system
functionality.

Make it not required, in order to support older versions of slap library.

Default to started, in order to support usual scenarios, when all is started
automatically.

Thanks to partially reverting "Use only externally provided buildout."
(commit 2a0bbcc9) it is possible to use
slapgrid with provided buildout binary, but no one is forced to follow this
way, as old style internal bootstraping procedure is available.

Conflicts, manually merged:

	slapos/grid/slapgrid.py
	slapos/grid/utils.py

Allow to have not defined buildout binary.

This functionnality is already provided by request.

Clean up the test because this tests and scripts were moved to erp5_credential. In testVifibCredential have only one test to validate if feature of subscription works in vifib context as expected.

Use by default checkUserCanChangePassword, but as in ERP5 users do not have
such persmission to Person document which defines them, check if logged in user
login is same as document reference.

Prove that user can request and revoke certificate for himself.
Prove that user cannot request twice the certificate.
Prove that user cannot request nor revoke certificate for another one.

Note: Currently failing, because users cannot set own passwords.

It allows to get/revoke certificates for Person. Protected in same way as setting Person's password.