New module dependencies.
New onlp_sys_platform_manage_*() interfaces.

onlp_sys_platform_manage_now()
------------------------------
This function performs any pending platform management tasks through a combination of common code and
the platform-provided onlp_sysi_platform_manage_* functions.

Platform management functions are scheduled through a timer wheel for different frequencies depending upon
context. onlp_sys_platform_manage_now() will call all management handlers who's execution deadline has expired.

This function does not block except in the course of execution of the individual platform management handlers.

onlp_sys_platform_manage_start()/stop()
---------------------------------------
This function manages a separate thread which calls onlp_sys_platform_manage_now() at required intervals to
maintain the current platform asyncronously.

start() -- Starts the management thread.
stop() -- Stops the management thread.