GitLab

* move unit tests to specific folders

* fix path error

* remove some assertions

* fix ignore path

* recursive scanndir

* support python3.5

* update and add tests

* resolve comments

* remove is_str

* remove supports for python 2.7

* fix the unit test for python 3.5

* add python 3.8 in CI

* try ubuntu 18.04 as the environment

* add copyright header

* change # to // for cpp files

* add yapf and isort to travis

* minor formatting

* remove blank lines

* skip unit tests for progressbar when python2

* update travis to ubuntu 16.04

* use a newer version ffmpeg

* add -y to add-apt-repository