Add SSL support to NZBGet sensor

[tboyce021]

Description:

Adds support for SSL hosts to the NZBGet sensor.

Pull request in home-assistant.github.io with documentation (if applicable): home-assistant/home-assistant.io#2616

Example entry for configuration.yaml (if applicable):

sensor:
  platform: nzbget
  host: nzbget.domain.com
  port: 443
  ssl: true
  monitored_variables:
    - download_rate
    - download_size

Checklist:

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated in home-assistant.github.io

If the code communicates with devices, web services, or third-party tools:

• Local tests with tox run successfully. Your PR cannot be merged unless tests pass
• New dependencies have been added to the REQUIREMENTS variable (example).
• New dependencies are only imported inside functions that use them (example).
• New dependencies have been added to requirements_all.txt by running script/gen_requirements_all.py.
• New files were added to .coveragerc.

If the code does not interact with devices:

• Local tests with tox run successfully. Your PR cannot be merged unless tests pass
• Tests have been added to verify that the new code works.

[mention-bot]

@tboyce021, thanks for your PR! By analyzing the history of the files in this pull request, we identified @justyns, @fabaff and @jabesq to be potential reviewers.

[fabaff]

Looks good to me 🐦