New DataEntity classes
Added supplier method to builder for FunctionFeed pollers
Use single character generic parameter type names
Update example usage for BasicEntity
Added configuration key for polling period
Added test for DataEntity
Changes from @aledsage review comments
Periodically log datagrid usage
location.unmanage: remove state from storage
Merge pull request #1301 from aledsage/feature/log-storage-usage

Periodically log datagrid usage
Fix StartableMethods.stopSequentially

- need to mark sub-tasks as inessential; otherwise failure of one
  will cause all subsequent tasks not to be executed!
Fix MySqlNode feed termination

- was not stopping feed (and was doing unnecessary extra ssh
  because was using separate SshFeed instance for each sensor)
stopSequentially: incorporate review comments
Merge pull request #1306 from aledsage/fix/stopSequentially

Fix StartableMethods.stopSequentially
Merge pull request #1160 from grkvlt/feature/data-entity

DataEntity