Various changes

If there's anything here you don't like, let me know and I'll remove it. First time doing anything with Android apps so this is really just practice/learning how to do small things. If there are better/more efficient ways to do things, please let me know.

1. Add image description for QR code image

2. Change repo_details Name title from 'Aurora Droid' to 'Respository Name'

3. Remove 'Optional' hint when Fingerprint field not filled out. Hints were overlapping.

   • Instead, rename the hint to 'Fingerprint (Optional)'. This does give me a warning about not using a linked string value, but I'm not sure if that's something you require.
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4. Import some drawable .xml's from Aurora Store, so that the settings menu has a bit of color. Only added what is required for the settings menu.

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5. Added a link to the Aurora Services repository when services are unavailable. Closes #37 (closed)

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