Rework how we handle seed phrases in the examples

[jrriehl]

Currently, when multiple people run examples at the same time, they are likely to get sequence mismatch errors on the registration transaction. This will become more and more prevalent as we get more users.

One solution would be to force the users to enter their own seed phrase for these examples, but feel free to suggest other options.

[Archento]

+1 for forcing of the seed to be put in manually and also for enforcing a seed structure like 12 word mnemonic phrases or something similar

[Archento]

First part is handled in #260
enforcing seed structure will be handled separately.

[jrriehl]

Reopening because the examples PR is not yet merged.