Cxflow-tensorflow

- simple RNN blocks `cxflow_tensorflow.models.rnn_stack`
- new cnn block `GlobalAveragePoolBlock`
- `DecayLR` hook now inherits from `EveryNEpoch` allowing to set up step learning schedule
- minor fixes

Hotfix pypi package.

Fix pip 10.0 issue.

Hotfix for pip 10.0.

Release 0.4.0 features substantial refactors, extensions and tests.

Major features
- Add `conv` blocks
- Add `cnn_encoder` and `cnn_autoencoder`
- Add `smooth_l1_loss`
- Add `FrozenModel` for tf frozen graph inference
- `GraphTower` and `BaseModel` refactored to separate files
- Add signal monitoring and extra (scalar) outputs to `BaseModel`
- Remove `model.restore_model_name` option of `BaseModel`
- Cover 100% of the code with tests


Minor updates
- Improve `DecayLROnPlateau`
- Smart images scaling in `WriteTensorBoard` hook
- `bin_stats` now accepts `suffix`

Minor patch for **cxflow** v0.10.1.