Sample: reboot vm example

I added an example to reboot a vm (forcibly) using ResetVM_Task. You can enter a UUID, an IP, or a DNS Name to search for the vm.

I also put the WaitForTasks from the poweron example into a taskops module and renamed the function to follow pep8 conventions.

I also noticed one of the new examples ```create_random_marvel_vms.py``` used requests so I added that to the requirements file.