Allow auto remove old dbsnapshot files

Related commits can be checked here:
HKUST-VISLab/vismooc-data-server-haha@ecde66c
HKUST-VISLab/vismooc-data-server-haha@2024a7f
HKUST-VISLab/vismooc-data-server-haha@207a349
HKUST-VISLab/vismooc-data-server-haha@8c3f1a7
HKUST-VISLab/vismooc-data-server-haha@ce57475

The test cases can be checked here:
https://github.com/HKUST-VISLab/vismooc-data-server-haha/blob/dev/test/Processor/HKMOOC2MongoProcessor/test_fetch_data.py

Fix the override section problem

data server fix and test case:

• HKUST-VISLab/vismooc-data-server-haha@6975caa
• HKUST-VISLab/vismooc-data-server-haha@1c71220

web server fix and test case:

• HKUST-VISLab/vismooc-web-server-haha@b79b85f

Fix some issues

• B2018-08-14-01
  fix in HKUST-VISLab/vismooc-front-end-haha@e733da7
  

• B2018-08-14-02
  fix in HKUST-VISLab/vismooc-data-server-haha@2eea399
  and
  HKUST-VISLab/vismooc-data-server-haha@bfc8342
  

• B2018-08-14-03
  fix in HKUST-VISLab/vismooc-front-end-haha@2cf2d80
  

Improve the docker-compose file and config example

• Improve the docker-compose file
• Improve the config example

Fix the db mount point problem

• fix the mount point problem of MongoDB docker
• update the example config file

Fix the default userUrlProfile problem

see the commits:

• HKUST-VISLab/vismooc-web-server-haha@c925a91
• HKUST-VISLab/vismooc-web-server-haha@1308452

Test reports:

• https://travis-ci.com/HKUST-VISLab/vismooc-web-server-haha/builds/79157771

Auto login and skip empy publish-branch

v0.4.36

update

Fix some minor issues of front-end

v0.4.35

update

Fix a front-end color schema problem

v0.4.32

update

Fix the ip country issues due to daily re-processing

data-server

test cases:

1. test_load_data_without_database
2. test_load_data_with_database
3. test_process_generate_users
4. test_process_update_user_ip_country
5. test_process_user_ip_country_with_none
6. test_process_user_ip_country_with_exception