Config option to disable ssl verification for methods/reloaders

```
time="2018-09-07T19:58:50Z" level=error msg="ButlerConfig::Handler()[count=5]: Cannot retrieve butler configuration. err=Get https://foo.owns.com/butler/butler.toml: x509: certificate is valid for bar.owns.com, not foo.owns.com"
time="2018-09-07T19:58:50Z" level=error msg="ButlerConfig::Handler()[count=5]: done."
time="2018-09-07T19:58:50Z" level=warning msg="main(): Sleeping 5 seconds."
```

Start by tracing the ButlerConfig handler and the methods/reloaders involved in retrieving the butler.toml URL; the issue names no files or tests. Determine where SSL verification is configured and how a new option should apply, then verify that disabling it allows the reported certificate mismatch case without changing the default behavior.

Written by the indexing model from the issue text.