Replace HTTPSConnection in NEC plugin

Replace HTTPSConnection in NEC plugin PFC driver with Requests.

SSL Verification is from now on enabled by default.

This changes the default behaviour and is the primary intention of this
change: verify SSL certificates.

This might break existing configuration/setups where the SSL certificate
used by the NEC PFC driver would not pass the verification.

SecurityImpact
DocImpact
Partial-Bug: 1188189

Change-Id: I1e5fdc9c2ed5b812aa6509d1639bd499acc5c337
(cherry picked from commit 264b4a2523c165640f17aa4837f87ddfd0b49640)