* Add Database source
* Add DatabaseSource source and database_* script for oal
* Enable Database_Indicator
* Add file license
* Rename DatabaseService to ClientDatabase. In the future, we may have real database server monitoring.
* Add query database from H2
* refactor
* update submodule
* refactor
* Fix style
* Fix: unknown tag error
* fix checkstyle
* Move oal tool back into main repo, and fix compile issue.
* Fix two bugs.
* Remove all generated codes.
* Make all oal generated codes out of source control.
* Make mvn compile and package work.
* Fix test cases.
* Make compile right and provide new documents.
* Remove an unnecessary tokens file.