Add DatabaseCleaner gem to avoid transaction with multi connections
Test has_many & belongs_to relation with .using
Using as scope: Model.using(:slave1).xxx.yyy
v0.0.2
Refactor: scope style is more readable than block style
add rake spec task
create db before spec
Merge pull request #1 from winebarrel/fix_spec

added spec task to rake
Unify quoatation style