Update BIP44 derivation path to m/44'/7070'

[NiKrause]

Please update everywhere in DoiWallet:

NiKrause/coins@df91b0b

Question:

1. What happens with existing wallets? Is the new derivation path used to generate addresses? Or only for new wallets?
2. When importing a seed can we specify an old bip (in this case 0 or in the case of ElectrumDOI 7)?