Adding a health toggle for disable mode

[elico]

Currently the health check uses a bool to enable the health function.
It would be smart to add a disable toggle at:
https://github.com/mkalus/goStatic/blob/master/main.go#L97

It can be changed via a SIGHUP or any other OS Signal operation.

A PR will be here soon..

[PierreZ]

Hi, looking forward for your PR 😄