Update migrations

[nodech]

Update Migrations

Old migrations depend on the methods and states that may be broken by the future updates to the codebase. This PR attempts to fix old migrations to reduce depenencies to the codebase. For example, Change address migration is currently broken, if user were to migrate from earlier non-fixed versions (e.g. v2.1.0)

This PR attempts to go over all migrations. Review and fix test cases and migrations:

• WDB
  • [x] MigrateMigrations
  • [x] MigrateChangeAddress
    • This can be further detached from the actual code, but currently still depends on wallet/walletkey, wallet/path and wallet/records.MapRecord.
  • [x] MigrateAccountLookahead
  • [x] MigrateTXDBBalances
• ChainDB
  • [x] MigrateMigrations
  • [ ] MigrateChainState
  • [ ] MigrateBlockStore
  • [ ] MigrateTreeState

[coveralls]

coverage: 68.551%. remained the same when pulling 8402cd00be09b3683b23bea974afb942d3be007a on nodech:update-migrations into 106fbfaacf4f154ee0e81712409b907c621f6e74 on handshake-org:master.

[coveralls]

coverage: 68.579% (+0.03%) from 68.551% when pulling bc98d66b3ee8c400257a472b1d499e7c019e00b5 on nodech:update-migrations into 106fbfaacf4f154ee0e81712409b907c621f6e74 on handshake-org:master.

[coveralls]

coverage: 68.621% (+0.07%) from 68.551% when pulling a550b13b8a3f6e6407a63ec667c9b86477a41627 on nodech:update-migrations into 106fbfaacf4f154ee0e81712409b907c621f6e74 on handshake-org:master.