message: Add missing log entry and release date
diff: # CHANGELOG
  -## 0.7.0 (not yet released)
  +## 0.7.0 (2020-02-26)
  **cosmwasm**
  region and serde's `from_slice`
  - Rename `Params` to `Env`, `mock_params` to `mock_env` for clearer naming (this
  is information on the execution environment)
  +- `Response.log` is not a vector of key/value pairs that can later be indexed by
  + Tendermint.
  **cosmwasm_vm**
  