Sweep of assets, and restricted assets

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Asset sweep has been added but it is broken.
The iOS version of RVN Wallet works and sweeps RVN and Assets one at a time (asks for each asset).

Add/Fix this functionality in Android RVN Wallet.

Test:

• Sweep just RVN
• Sweep RVN and 1 asset
• Sweep RVN and 3 assets (skipping first)
• Sweep RVN and 3 assets (skipping last)
• Sweep RVN and Restricted Assets

Consider sweeping assets first so there's enough RVN for fees.

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amount=USD$500.00 paid_in=RVN status=open info=https://github.com/RavencoinFoundation/gitRVN