support arbitrary fields of KiiUser
added object query
cleaned up the implementation of KiiClause and KiiCondition
Merge pull request #5 from ssmi1975/pr_fix_kiiuser_fields

support arbitrary fields of KiiUser
Merge pull request #6 from ssmi1975/pr_bucket_query

added object query
今更ではありますが、ConditionよりQueryParamsのほうが適切かなという気はしてきました。（HTTPもquery parametersと呼ぶので）
fixed KiiCondition
Merge pull request #7 from ssmi1975/pr_bucket_query

fixed KiiCondition