pyDAL 15.07

2015 July release

• Added smart_query support for 'contains' on fields of type 'list:string'
• Implemented correct escaping for 'LIKE'
  (see #212)
• Added support for ondelete with fields of type 'list:reference' on
  MongoDBAdapter
• Improved BasicStorage performance
• Added arithmetic expressions support on MongoDBAdapter
• Added aggregations support on MongoDBAdapter
• Table.validate_and_insert and Table.validate_and_update methods now
  validates also empty fields
• Added support for expression operators on MongoDBAdapter
• Several bugfixes