create vm blocking and non_blocking are working same.

[gjagtap]

create vm,

1. blocking : it will block till vm is created.
2. non bloxking : it will create vm in parallel, and return.

In current implementation , after popen, we communicate, it will wait internally. there is no point for adding extra wait call.

I think non blocking is not yet implementation

for reference https://docs.python.org/3.4/library/subprocess.html
Popen.communicate(input=None, timeout=None)
Interact with process: Send data to stdin. Read data from stdout and stderr, until end-of-file is reached. Wait for process to terminate. The optional input argument should be data to be sent to the child process, or None, if no data should be sent to the child. The type of input must be bytes or, if universal_newlines was True, a string.

[gijzelaerr]

@MaralAfris added that code a while ago. Feel free to do a PR to fix it!