Added a downstream text label to the debug console.
Refactor data rate calculations in DebugConsole.
Simplify calculations by assuming we only care about rates in kB/s.
Removed various bits of dead code.
Renamed getNominalDataRate to getConnectionSpeed. Also added upstream/downstream data rate functions to all Link classes.
Add display of the outgoing data rate to the debug console widget.
Don't update the ConsoleDebug data rates UI if no link exists (like on startup).
Moved configuration constants in DebugConsole to proper static const types.
Merge pull request #437 from Susurrus/simpleCheckRates

Add display of the upstream data rate to the Debug Console
Make OSG conditional
Merge branch 'OSGFix' of https://github.com/DonLakeFlyer/qgroundcontrol into OSGFix