implement test test_ComputerPartition_request_SlaveInstance_noSoftwareInstance. This is to check that one Slave Instance will wait allocation if no exists Software Instance installed

Revert "update local roles to test_vifib_customer_a user". Call updateLocalRolesOnSecurityGroups() after login is not allowed. The user was configured correctly on vifib_bt5

This reverts commit de06243f.

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.

add steps to test_Person_request_SlaveInstance_with_Different_User. This test is to check if user B can declare a slot of slave instance in computer partition used by user A

implement test_Person_request_SlaveInstance. This test validates if is possible create Slave Instance with the same user used to create one Software Instance

remove bt5 because this bt5 is not required anymore. Now, you can configure the default assignment to vifib users in portal_preferences interface

remove transaction because it is not required. The goals is reuse the transaction request_software_instance

This functionnality is already provided by request.

add workflow method to request one slave instance. The script added is a blank script; only to commit a skel of Slave Instance

remove form used to list the Slave Partitions. This form is not used anymore because Slave Partition is obsolete

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.