Implementing fix for POST request retry issue

If a POST request is sent when the Datera box is under extremely heavy
load, there is a scenario where a reply may not have been recieved
before the underlying connection is dropped.  The retry code tries again
and recieves a ConflictError in this case which was previously being
propagated up to the user.

This patch fixes the issue by catching that ConflictError (only for POST
requests) and translating the POST request to a GET request for
subsequent polling until a response is recieved.  This response is then
processed and returned normally.

Incrementing version for build

Incrementing version for tag

Incrementing to v1.2.20

Bugfix where disable_log parameter caused exception

Adding verification support

* Use the 'verify' keyword parameter to enable it
* 'verify' is passed directly to requests, so it has the same
  behavior as vanilla requests
* The cert parameter will now allow for passing in a bundled cert/key
  combo file (for example, a *.pem file).

Fixing bug in scaffold that overrode earlier API versions with latest

Updating version

Updating the constants file

Fixing bug where ldap_server information was not passed with login

* Also dropped requirement for argparser from scaffold UDC config