Investigate the Android Keystore system for e.g. encrypting the Tox profile

[robinlinden]

https://developer.android.com/training/articles/keystore

[beaglesnuf]

Moreover, perhaps support for importing encrypted profiles. Exporting the existing profile can perhaps be set within Settings in order to increase the number of steps required for profile export.

[robinlinden]

@beaglesnuf as of #683 importing encrypted profiles is supported, but it hasn't been part of a release yet!