This reverts commit 08a8c1d1.

* test=develop, change md5 for patchELF

* test=develop, update protobuf

* test=develop, update protobuf in Dockerfile used by CI

* test=develop, install requirements before start for Linux

* test=develop, uninstall protobuf on linux brefore install latest version of it

* test=develop, fix pip

* test=develop, install protobuf in linux

* test=develop, fix patch ELF install failed

* test=develop, change md5 for patchELF

* test=release/1.3, cherry-pick

test=develop

test=develop

Disable the finding of python, swig related packages completely when WITH_PYTHON and WITH_SWIG_PY are set to OFF.

* Do not use `virtualenv` in Docker
* Split unittest into many target, make them parallel

* Expose paddle.framework by pybind11

* Export paddle.framework.{Scope, Variable} to paddle.v2.framework.core.
* See python/paddle/v2/framework/tests/test_scope.py for Python usage
* See paddle/pybind/pybind.cc for C++ bind code.

* add copyright

When using system python, "pip install" needs root previlege. Using virtualenv to avoid this.