Fixed logging of old value for issue estimated and spent time.
Fixed logging of old value for issue estimated and spent time.

Problem with previous logic was that if you only updated time unit or points column that had value 0, log's old value would be "Not estimated" since other columns unchanged values weren't taken into account.

deshion/thebuggenie,deshion/thebuggenie,SysBind/thebuggenie,Rvanlaak/thebuggenie,milkyway-git/thebuggenie,LogosLabs/thebuggenie,LogosLabs/thebuggenie,praveenscience/thebuggenie,thebuggenie/thebuggenie,thebuggenie/thebuggenie,Rvanlaak/thebuggenie,azaghal/thebuggenie,nrensen/thebuggenie,Rvanlaak/thebuggenie,thebuggenie/thebuggenie,praveenscience/thebuggenie,azaghal/thebuggenie,thebuggenie/thebuggenie,LogosLabs/thebuggenie,thebuggenie/thebuggenie,praveenscience/thebuggenie,deshion/thebuggenie,azaghal/thebuggenie,SysBind/thebuggenie,nrensen/thebuggenie,milkyway-git/thebuggenie,praveenscience/thebuggenie,SysBind/thebuggenie,SysBind/thebuggenie,LogosLabs/thebuggenie,deshion/thebuggenie,milkyway-git/thebuggenie,nrensen/thebuggenie,azaghal/thebuggenie,nrensen/thebuggenie,milkyway-git/thebuggenie,Rvanlaak/thebuggenie