Add support for LongColumn
make tests pass
make valueType configurable
return correct valueType
Revert "return correct valueType"

This reverts commit 0b42ca4c75a451e221bf74d312693f9eead9f945.
Revert "make valueType configurable"

This reverts commit 6f60a3f60437ddfff2065110d8622ef218fd4b65.
review comments - cleanup ColumnSelectorFactory
review comments
merge changes from 0.7.x branch
Merge pull request #805 from metamx/long-column

Long column Support