Fix asset database error, fix unit tests

[blondfrogs]

Problem:

When a user would shutdown the wallet, after they issued an asset, and transfer an asset within a couple blocks then performed a wallet shutdown.

When the wallet is loaded back up, it would undo a certain amount blocks to verify the validity of the most recent chain. This allowed the database and memory to become out on sync because it was Writing the transfer asset data before the issued asset data.

Fixed - This change fixes the problem by changing the order the assets database performs its Write/Erases, so they overlap in the correct order.
Fixed - Fixed units tests that broke when #223 was implemented

[cfox]

👍