Make sure that debugger isn't included in production environment.
Merge pull request #9638 from siong1987/debugger

Make sure that debugger isn't included in production environment.
document habtm join-table name with custom prefix [ci skip].

Closes #9643.

The logic was introduced with 46492949
Merge pull request #9645 from senny/9643_habtm_wrong_table_name

document habtm join-table name with custom prefix [ci skip]