* fixed a bug about unzip

* added a test case for MnistModelLoader

* cleared warnings in the UnitTest project

* Upgrade NumSharp with signature.

* Testing gradients function: (#307)

- Concat
- LGamma
- Tanh
- Slice

* Adding new ctor for `Session` (#309)

Meant to be a shortcut to directly set some basic configuration.

E.g.

```
var sessionOptions = new SessionOptions();
sessionOptions.SetConfig(new ConfigProto
{
   LogDevicePlacement = true,
   InterOpParallelismThreads = 4,
   GpuOptions = new GPUOptions
   {
      AllowGrowth = true,
      PerProcessGpuMemoryFraction = 0.12
   }
});
var session = tf.Session(sessionOptions);
```

Adding `AbsGrad`

To be aligned with Tensorflow, introducing also `Sign` operation
and its gradient.

* fix strided_slice_grad type convention error. #307

* added a static load method for MnistModelLoader

* adjusted the assembly name for hub

* add Prediction function for Transfer Learning

* fixed the path combining issue

* Init TensorFlow.Text project. put all UnitTest and Example into one project.

* Predict image category in bootleneck file.

* Adding `IsNan` operation (#315)

Exposing also the `IsFinite` one.
Unit testing both operations.

* change bottleneck file to raw image as input for transfer learning.

* remove unnecessary projects (#316)

* implementing some additional methods (#317)

* got rid off the reference to the TF.NET

* updated project file for packaging

* removing unused namespaces

* implementing Tensor to scalar and scalar to tensor conversions

Unit testing the gradient too.

Also unit testing all the operator cases.

Also unit testing all the operator cases.

Change nest.flatten to generic.

2: Upgrade Microsoft.ML.TensorFlow.Redist to v1.14.

This reverts commit e0e2bd13ef.

# Conflicts:
#	README.md
#	src/TensorFlowNET.Core/Sessions/_FetchMapper.cs