Add additional settings, clear status message controls, assorted fixes

[david-c-kline]

This change adds settings for:

• expanding credentials and network settings by default in the connect dialog
• providing default ssid and network key for new connections
• defaulting to using installed device certificates during connection

It also adds Clear Status Message (broom) buttons in the following locations:

• To the right of the main window status message bar
• In the Device Control group (clears selected device messages)
• In each Device Monitor Control to the right of the status message field (here the button is labeled with an X, due to size)

Assorted fixes include:

• Improved identification of a previously installed version of an application at install time
• The Unregister (aka Forget) devices button now honors the device selection state (used to unregister all devices)
• Close all apps no longer closes MixedRealityPortal.exe on Windows PCs (doing so would turn off Windows Mixed Reality headsets)
• Add exception handling and status messages to main window and device monitor control commands.
• Removal of unused Status Message in Manage apps dialog
• Minor layout changes in Get install files dialog
• Removal of support for ARM dependencies in Get install files dialog (HoloLens is x86, Windows PCs are x86/x64).

Closes #100 Closes #111 Closes #139