Improve wifi connectivity logic

[knorrium]

I had a power failure and after it came back, the Nerdminer turned back on but did not start mining until I restarted it again when the router was also back up.

I'm not sure if it did connect to wifi but didn't start mining or if it was in an error state while the router was out. The screen displayed it was up for 48h with no block templates, no hash rate, and no shares.

[BitMaker-hub]

hmm.. we have to check