* Fix the Let's Encrypt handler by listening on a valid address
Also handle errors in the HTTP server go routine, return a fatal error
when something goes wrong.
Thanks to @gbl08ma for finding the actual bug
Here is an example of the error handling:
2018/12/11 14:23:07 [....io/gitea/cmd/web.go:87 func1()] [E] Failed to
start the Let's Encrypt handler on port 30: listen tcp 0.0.0.0:30: bind:
permission denied
Closes#5280
* Fix a typo