#149 - [trader] make logging informative and more succinct

[trizin]

Fixes #149

Changes proposed in this PR:

• Make logging informative and more succinct

Logs (ran against testnet):

python3 pdr_backend/trader/main.py
Getting feed for 0x8db30338c5f09381cd2644bf7b4b8ea578e248a9

--------------------------------------------------------------------------------
Config:
TraderConfig={private_key=0xhi, rpc_url=https://testnet.sapphire.oasis.dev, subgraph_url=https://v4.subgraph.sapphire-testnet.oceanprotocol.com/subgraphs/name/oceanprotocol/ocean-subgraph, trader_min_buffer=60, owner_addresses=[], pair_filters=['XRP/USDT'], source_filter=[], timeframe_filter=[], web3_config=<pdr_backend.util.web3_config.Web3Config object at 0x7f7ee551b6a0> /TraderConfig}
----------------------------------------   Processing [Feed 0x8db30 XRP/USDT|binance|5m]  ---------------------------------------- 
Epoch 5647241
Seconds remaining in epoch: 255
      [Feed 0x8db30 XRP/USDT|binance|5m] has a new prediction: 0.0 / 0.01.
----------------------------------------   Processing [Feed 0x8db30 XRP/USDT|binance|5m]  ---------------------------------------- 
Epoch 5647241
Seconds remaining in epoch: 249
      Done feed: already traded this epoch
----------------------------------------   Processing [Feed 0x8db30 XRP/USDT|binance|5m]  ---------------------------------------- 
Epoch 5647241
Seconds remaining in epoch: 244
      Done feed: already traded this epoch

[trentmc]

Looks good. One small thing to add. Once you've done that, go ahead and merge