Add support for https listen

[SevansD]

We can set on front https endpoint, but without any proxy (nginx etc) can not listen https with webwire server. This pr add support for tls listen

[coveralls]

Pull Request Test Coverage Report for Build 324

• 8 of 20 (40.0%) changed or added relevant lines in 2 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.3%) to 82.137%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
server.go	5	17	29.41%
<!--	Total:	8	20	40.0%	-->

Files with Coverage Reduction	New Missed Lines	%
message/testutil.go	2	81.36%
<!--	Total:	2		-->

Totals
Change from base Build 323:	-0.3%
Covered Lines:	2621
Relevant Lines:	3191

---

💛 - Coveralls

[romshark]

Currently, to be able to use TLS encryption a custom HTTP server hosting the webwire server must be set up. It's demonstrated in the external example. But It'd probably be a good idea to add a new constructor function with TLS support, like:

func NewSecureServer(
    implementation ServerImplementation,
    opts ServerOptions,
    certFile,
    keyFile string,
)

to newServer.go

[SevansD]

35

[romshark]

35 is now resolved.