Make maximum connection delay a configurable option

[tkas]

In cases, where connectivity is not on all the time, 20min delay for connectivity check may be too much. Please consider making the maximal delay a user configurable option. (If connection manager can be added as another option being used in parallel with regular checks, it may help as well).

(previous discussion in issue #171)

Thank you

[JPMakesStuff]

I would also greatly appreciate this!