upgrade system and fixing errors and add rest api and etc -- 2

1. 0x protocal update v1 to v2 - 1300$ 10 days 2. Restful API, Websocket API, Document - 2500$ 20 days 3. Add Admin Panel feature - 1000$ - 10 days 4. Ledger nano login - 300$ - 3 days 5. add usdc market - 400$ - 3 days 6. localization, metamask localization - 200$ - 2 days 7. landing page mobile responsive - 200$ - 2 days 8. live chat, metamask, language selection, 24 volume at header, ropsten, tm market scroll error, market array(desc, asc error fixing), download pdf, send message, trading view - 1000$ - 7 days Total: 6900$