Connection Checks

Includes the code from #12 to ensure that empty credentials are not passed to a broker if they are omitted from the connection settings.

UI Changes

After feedback on the UI from @andysc, several features have been modified for a smoother user experience.

Namely:

1. The "Save" button in the settings panel has been switched with a Cancel/Save combo for users who just want to inspect their settings, not change them.
2. The "Settings Cog" has been replaced with a "Connections Setting" button just beneath the GlowOrbs "last updated" dialog.

Also:

1. The app icon has been updated so it looks a little brighter than before.

First public release

This is the first version of the GlowOrb emulator that has all of the features / functionality that I wanted it to have when I first had the idea to make one.