* support python 3.8

* fix python2 compatibility

* remove py38 unittest since paddle don't support python3.8

* stop using pickle cloud to transmit the remote class

* ping the master before connection

* yapf

* fix comments

* remove the useless library

* install ping for the docker environment

* remove protobuf intallation

* remove evokit test

* Add UnitTest for DeepES

* update Dockerfile

* only unittest

* remove the commented lines and empty functions.

* update CMakefile

* add optimizer unittest and torch demo test

* use optimizer_factory and add fail unittest case

* remove duplicate files, and simplify unittest

* teamcity test

* delete test case

* remove comment line

* shield progress display of downloading and unzip libtorch

* remove deepes torch demo test

* delete useless comment

* torch test env

* Update build.sh

* update torch unit test

* upgrade unit test to reduce test time

* minor change

* fix the bug in unit tests

* fix the bug in build.sh

* Update build.sh

* Update test.sh

* fix a potential bug that will hung the test

* then

* solve the problem in documentation

* add unittest for compling the docs

* record the time of change

* remove unused requirements

* reduce font size of the changelog

* add test for import parl

* fix error of check_style

* change pip source

* refine naming

* Update README.md

* Update Dockerfile

* Update build.sh

* refine remote module, add heartbeat machanism and unittest

* yapf

* yapf

* support get ip address in CentOS, add dependence

* yapf

* add dependence in Dockerfile

* refine message_tag, Compatible with Python2 and python3

* refine unittest and comments

* remove ParlError, use to_pybytes api to compatible with Python 2 and python 3

* Not need to use to_pybytes

* use parl-test docker image for unittest, which has python2 and python3 env

* test different release order of sockets

* test for different closing way fo context and socket

* tmp commit for debug in teamcity

* tmp commit for debug in teamcity

* tmp commit for debug in teamcity

* use zmq.context destroy to close multi-thread socket, refine RemoteError

* set linger=0 for command socket in RemoteObject

* remove close context unittest

* fix codestyle

* fix codestyle

* rename parl.remote to parl.remote_class; will not exit client when having errors in function call; use sepereate server port in unittest to avoiding closing server manually

* rename parl.remote to parl.remote_class; will not exit client when having errors in function call; use sepereate server port in unittest to avoiding closing server manually

* fix typo

* remove unnecessary try/except in reply loop of client

* import RemoteManager to parl; refine comment

* run unittest in python2 and python3

* refine structure of repo

* refine structure of repo

* add --fix-misssing

* fix teamcity

* add --fix-misssing

* update paddle version in python2