gvite-v2.9.0-release（Upgrade is needed）

Hard fork block height: 31305900
Hard fork time: 4:00 AM May 27, 2020 (UTC+0)

The hard fork will include the following updates:
Queue order submitting and cancelling, avoid cancel failing;
Allow agent cancel orders that submitted both by owner and agent;
Supply composite API for order submit, make submitting simpler.

SHA256(gvite-v2.9.0-darwin.tar.gz)= 8af5bce48b82717c45ad607aae1013f8144e890719f2c5c11cc824533b4db32e
SHA256(gvite-v2.9.0-linux.tar.gz)= fd6aad3b0a783ae6630474d033aa8e48603c03a55b7a59f1e4bbd5e59848a0b5
SHA256(gvite-v2.9.0-windows.tar.gz)= 31f905a3b635ae400b2ca3aa23263d225bc7ac3196e5a63c65292e6822e470cf