Bump requests to 2.2.0

Per sdague we are using 2.2.0 in the gate, let us
raise the min level to match that. We also need this
for oslo.vmware to work around a bug with file urls
(see change id Ie0635607847061c68c879e87db8f2541436f03d6)

Change-Id: I49ca94de4dc5e7cf09280e1119725846b5dfee36
Merge "Bump requests to 2.2.0"