Merge pull request #378 from cdmcnamara/develop

[FIX] Update host-meta-plugin and bridge-payments-plugin version to poin...
[FIX] Updated to conform to the latest gateway services protocol spec
Merge pull request #379 from cdmcnamara/updated-spec

[FIX] Updated to conform to the latest gateway services protocol spec
[FEATURE] Get and set last payment hash in database.

[FOLD] Use plain getColdWallet function.

[FOLD] Set current hash not previous hash.

[FOLD] Remove redundant lastHash if check.
Merge pull request #381 from ripple/last-payment-hash

LGTM