Fix race condition on sending data
Fix race condition on sending data

If data was sent prior to the activate payload response, the code
to calculate the maximum chunk could not suceed.  Correct this
by having sent data accumulate as pending until connected state reached.

Change-Id: I7c9aed67209b3526bd10cafeee0bae6b1b0ab85f

openstack/pyghmi,openstack/pyghmi,benoit-canet/pyghmi,stackforge/pyghmi