Chiron

Add the description in the README about the dependent package.
Add tf version
Remove unused package

Change the signal normalization to MEAN for better performance.

Improvement
A new RNA model with overall **>85%** accuracy.

Obtain **>60%** successful short RNA reads basecall pass rate when using [**BoostNano**](https://github.com/haotianteng/BoostNano) for preprocess. (from <20% successful short RNA reads pass rate of other basecallers).

This is a new version with a faster DNA model(10X faster and same accuracy) and pipeline optimization.

Update a new RNA model.
10X faster RNA inferencing.

Fix a bug that could cause the CTC decoding pipline stuck, replace tqdm module in chiron_eval.py with a self-written progress bar which is more stable(and almost equally fancy).
Improvement of the new model(DNA_default) on NA12878-WGS(human) benchmark dataset:

SUMMARY
Total reads:6080
Unaligned reads:3303 -> 1553
Deletion rate : 0.0930 -> 0.0847
Insertion rate : 0.0562 -> 0.0538
Mismatch rate : 0.0933 -> 0.0670
Identity rate : 0.8283 -> 0.8483

Remove the tqdm process bar inside the worker, which cause Chiron collapsed. And fix the description of the process bar.

New feature released: chiron_label.py
Enable label(re-squiggle) the DNA/RNA reads with a high success rate, label reads can be used to train new Chiron model.