Add WALA Event Module

I think we should continue to post event if some sysinfo is not collected. I will put   self.sysInfo["OSVersion"]=platform.system()+":"+"-".join(DistInfo())+":"+platform.release() and  self.sysInfo["GAVersion"]=GuestAgentVersion at beginning. so even exception happens those tow info are collected, and other information i don't think they are something we must have.