Enable import private key feature

[akshaynexus]

Since now PIVX has a TREZOR Blockbook based explorer which has similar api methods to insight-api, import private key function could be enabled to allow paper wallets to be imported to the iOS Mobile wallet.

[furszy]

There is no need for Trezor blockbook or any other specific explorer to import a key into the wallet, just the functionality needs to be coded.
Using a central data place to recover the balance fast or syncing the wallet all over. Both are doable options.