Updates to wifi-schedule plugin + new wifi-survey plugin

wifi-schedule has minor bugfixes only

wifi-survey has is mostly fully functional.
  Vendor lookup is enabled but requires a 750k+ file to be present. It is not. All vendors are "unknown" in an initial install.
  READ_ME.txt tells an adventurous user how to create the OUIs.js file required for vendor lookup.
  I will look into creating an opkg of OUIs.js for installation onto a USB drive or /tmp (which is where I used it).