added embedding rules, MonteCarlo(uncertainty) prediction and removed running of the tests on draf requests

Pmulinka/raytune

Removed condition from trainer on duplicated callbacks. Tab2Vec optionally returns pandas dataframes. Added unit tests for new functionalities and all notebooks follow now black coding style. All this relates to PR #55

code cleaned + added workaround for ¨ImportError: libGL.so.1: cannot open shared object file: No such file or directory ``` apt-get update apt-get install ffmpeg libsm6 libxext6  -y ```¨

* added RayTuneReporter callback
* adjusted history so it reports metrics per class in case of multiple values per metric. eg. multiple classes

* added notebook and 1 report for metrics

Fixed issue #53 related to the use of some transformer models without categorical columns

Jrzaurin/travis to actions

push and PRs only on master branch. Added the github actions badge and changed the adult dataset broken link

Jrzaurin/perceiver

Added docs. Re-design Additive Atttention accoring to their code. Add a few details on the docs and fix a typo

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Added a proper implementation of transformer models when needed and re-organised the transformers module for clarity

First commit towards the perceiver. Changed modularity so that embeddings are consistent accross models. Adding the perceiver also forced me to change the structure of the TabTransformer and SAINT

Saint