Added timeout to WPS mode

[rbreaves]

Uses WIFI_CONNECT_TIMEOUT variable in general.h from the espurna source code. (which is set to 60 seconds)

Not sure if this is a default behavior that got overlooked or is undesired, but I know I certainly prefer it as I have been deploying these smartplugs for family and friends that may accidentally knock these devices into WPS or AP mode when manually rebooting (this pull request only times out WPS mode).

[tonilopezmr]

I would suggest you define a new global variable like JUSTWIFI_WPS_TIMEOUT