hotplug modularization: move sources to a subdir

Signed-off-by: Tzafrir Cohen <tzafrir.cohen@xorcom.com>
Acked-by: Russ Meyerriecks <rmeyerriecks@digium.com>
hotplug modularization: split logic to scriptlets

* Device related operations are ordered in /usr/share/dahdi/handle_device.d/
* Span related operations are ordered in /usr/share/dahdi/span_config.d/
* In the future, span_config.d/50-asterisk should be moved to Asterisk.

Signed-off-by: Tzafrir Cohen <tzafrir.cohen@xorcom.com>
Acked-by: Russ Meyerriecks <rmeyerriecks@digium.com>
new "dahdi_waitfor_span_assignments" tool

* Allows waiting until all spans are "assigned" or "unassigned"
* Current implementation use a polling loop with sleep
* Future implementation may block on sysfs attribute
  (like waitfor_xpds is blocking on sysfs Astribanks attribute)

Signed-off-by: Tzafrir Cohen <tzafrir.cohen@xorcom.com>
Acked-by: Russ Meyerriecks <rmeyerriecks@digium.com>