Since these will almost always connect to an IP rather than a "real"
hostname, don't verify the SSL cert (if applicable). Also allow the
overriding of SSL verification via an environment variable.
As a consequence, to reduce spam, SSL warnings are disabled for urllib3.
Instead, we warn in the "Using cluster" output whenever verification is
disabled.
Provide pretty status bars to indicate upload progress for tasks that
perform large file uploads to the API ('provisioner ova upload' and
'storage volume upload') so the administrator can gauge progress and
estimated time to completion.
Use a different wait method of querying the node status every
half-second during the transition, in order to wait on the transition to
complete if desired.
Closes#72
Move all API calls to a new common function called call_api to
facilitate easier future changes. Use this function to implement API key
handling via request header value as well as integrate the request URI
generation and debug output handling.
Closes#65
