Added "alert on connect", changed design a little

[fluffyspace]

Hi. First of all, thank you for an amazing application and making it free and open source. It's not easy being the only contributor. I love the code you wrote.

I modified the application because I have a cat and I need to get a notification when it comes in range. It would also be amazing to add "passive mode" which wouldn't connect to iTag but rather capture Bluetooth advertisements so that more devices can listen to it. I'm aware that in passive mode the iTag doesn't send advertisements as often as in connected mode but it would be a nice feature.

This is the first time I'm contributing to a project on GitHub, I hope i didn't do bad. I checked for bugs and I couldn't find any, but I'm sure there are some because it's hard to be flawless.

What I did:

• change color of "forget" button to red
• change icon of "change color" button to color picker icon so that it's more obvious
• renamed some methods so it made more sense to me while I developed
• added alert mode to iTag's settings - no alert, alert on disconnect, alert on connect, alert on both
• added UUID (or how it's called) below iTag's name on main screen
• added RSSI text next to RSSI indicator and made RSSI indicator wider
• added text "Mode: connect/don't connect" to bottom left corner of iTag's display
• made Bluetooth icon change color based on connection status
• made iTag's opacity less when it's disconnected
• cut audios in Audacity to shorter length since it's repeating, to make files smaller
• added and changed translations

[fluffyspace]

I found new bugs I introduced. I will repair them before opening the pull request again.

[fluffyspace]

@dsame will you check it out?