* mv ps distributed dir

* fix

* add del auto_parallel

* add auto_parallel

* fix ps

* fix bug

* fix test bug

* fix test bug

* merge develop fix error

* merge develop fix error

* merge develop fix error

* add isort config

* isort all files

* update config

* re-blacken python code

* temporarily disable date and diff_py_file

* skip a format

* use yapf to format all python file

* yapf exclude two unittests file for they rely on writing and reading file, and format will break them

* disable diff_py_file because too many diff files cause command following failed

* add random varaiable transformations API for paddle's distribution package

* add TransformedDistribution API for paddle's probability distribution package

* add random variable transformation unitests for static graph

* replace math.prod which not support python3.7 with functools.reduce

* add Independent and TransformedDistribution distribution

* add unittests for constraint

* fix typo and AffineTransform sample code error

* add mean,variance,rsample abstract method for Distribution

* add beta distribution
* add kl_divergence and register_kl api

* extend Distribution baseclass for supporting multivariant distribution and prob method

* add ExponentialFamily base class and entropy using Bregman divergence

* add dirichlet probability distribution