Auto detection of system proxy settings & bug fixes.

Bug fixes:
- Color state (RED) would be calculated for observations reporting OVX (visibility and cloudbase not present, but are reported are parsed as 0 from NOAA); colour state for such observations will now be ommitted.
- Observations not having visibility or cloudbase present, had their respective variables set to 0 instead of null, causing the colour state to be miscalculated.