Insteon: Check if Active Message Exists Before Calling Success Callback

Additional fix to hollie/misterhouse#324
Merge pull request #366 from krkeegan/fix_success_callback

Insteon: Check if Active Message Exists Before Calling Success Callback
Insteon: Notify User if Startup Scan is Skipped Due to Bad Exit
Merge pull request #367 from krkeegan/insteon_startup_scan

Insteon: Notify User if Startup Scan is Skipped Due to Bad Exit