Simplify fastai tests imports

Install fastai from source and pinned version

Prevent fastai install from downgrading pytorch

Replace fastai tests using 1.x api

…ling up disk

Prune images previously built to prevent permanent gpu worker from fi…

…er images.

Update README to mention that GCR is the source of truth for our docker images

plotnine 0.5 is depending on matplotlib >= 3.0 which is not compatible with basemap.

Prevent upgrade of matplotlib

Upgrade anaconda base to 5.2.0

Install fasttext using pip git feature

Don't preload tensorflow and torch

Adding xvfb and xvfbwrapper

Add libGL1 to satisfy vtk dependencies

If fastai is used prior to tensorflow, an older version of libcudnn is loaded and tensorflow fails with the following error message:
```
tensorflow/stream_executor/cuda/cuda_dnn.cc:343] Loaded runtime CuDNN library: 7.1.2 but source was compiled with: 7.2.1.  CuDNN library major and minor version needs to match or have higher minor version in case of CuDNN 7.0 or later version. If using a binary install, upgrade your CuDNN library.  If building from sources, make sure the library loaded at runtime is compatible with the version specified during compile configuration.
```

Preloading for now (like before) until we find how to fix the issue with fastai

Preload tensorflow

Add MXNet GPU + GluonNLP and GluonCV toolkits

… add-tesseract

prevent mxnet from downgrading numpy

Allow parallel branch builds

…or wasSuccessful field.

…l: false.

Add optuna and tests.

… with cartopy.

Updates pip version as the latest version doesn't seem to have issues…

Document cuda compute compabilities

Add TensorBoard to Kaggle Kernels

Properly store access token so it can be used by credentials object.

Add tesseract, pytesseract, and utility packages

* Adds support for expiry of bigquery access token.

* Updates expiry of access token in tests.

* Sets expiry to a datetime instead of seconds to expiry.

* Add more typing information for kaggle_secrets.py