Error report delay/mute

#### Issue details
When connecting to a craft just after it boots/initializes, errors like Bad AHRS, Bad GPS, etc are reported in MP only to clear once the craft has booted properly and settled down.

Maybe a 10 or more second mute/delay could be in effect after connected and then unmuted to be able to report errors that are actually there, not ones that are always present when initializing.

#### Version
V. 1.3.xx
#### Platform
[ X ] All
[ ] AntennaTracker
[ ] Copter
[ ] Plane
[ ] Rover
[ ] Sub

#### Airframe type
Multirotor / Plane

#### Hardware type
Pixhawk, AUAV-X2, Cube

#### Logs
N/A

No files or tests are named. Start by locating Mission Planner's connection initialization and Bad AHRS/Bad GPS error-reporting entry points; define completion as suppressing startup-only errors briefly after connection while still reporting persistent errors afterward.

Written by the indexing model from the issue text.