Refactor service interface, control. Move it to core.
Move controls to core

Name changes in services:
rename control and interface service to more explicit names.

For example, this patch replaces:
from openalea.oalab.service.interface import new as new_interface
with
from openalea.core.service import new_interface

Full changed list:

Services interface:

guess -> guess_interface
get_class -> interface_class
get_name -> interface_name
get -> get_interface
check -> check_value
new -> new_interface
names -> interface_names
default_value -> interface_default_value
alias -> interface_alias

Services control:

new -> new_control
get -> get_control
register -> register_control
unregister -> unregister_control
create -> create_control
group -> group_controls