Move common ads fields (keyword and campaign type) to common logic.
Merge pull request #39 from fangdiantong/yesenfei

add the baidusem keyword_type column
Merge pull request #40 from fangdiantong/yiling

Move common ads fields (keyword and campaign type) to common logic。
Refactor and move all common methods to Base/Util class.
Rename MongoRowConverter to AdDataConverter.
Add several interface for MongoRowConverter: get campaign / region / device
Merge pull request #41 from fangdiantong/yiling

Major refactory on MongoRowConverter  to AdDataConverter
fixed the baidu sem device has no data bug