update to generate features for more users
refactor the db data loader part
move escape function in Data class to a separate util function
Remove old code in Data.py
rename Data.py to data_source.py
refactor the data source. Create UserTable and SkillTable
use environment variable to set database
update gitignore to ignore test shell scripts
Merge branch 'develop'

Conflicts:
	api.py
	data_source.py
	match.py