Add support for skipping tls verification when performing HTTPS check

[anthcourtney]

Picking up from #447 and incorporating the update in the consul api which now expects a boolean.

[jharley]

Thank you for this :+1:

I just cherry-picked your commit into my fork, but needed to change line 106 to this to get it to compile:

                       check.TLSSkipVerify, _ = strconv.ParseBool(tls_skip_verify)

Commit is here: https://github.com/jharley/registrator/commit/6fcc1210d0ee005597f51ef8f026839994fa1e90

[anthcourtney]

@jharley - Thanks, I consumed your change in my fork.

[alexinthesky]

please merge

[mikepietruszka]

Any plans to get this merged and released? Would really love this feature.

[jonfreedman]

I agree, can we please merge this and push a new master image to dockerhub?

[yardik]

Aaah please merge this.

[jharley]

@anthcourtney Can you rebase this to resolve the conflicts, and maybe we can get it into mainline?