Bugfix and tests for CHAR(N) and VARCHAR(N)

Fixed a bug when setting the length in reading/write text files for CHAR(N).
Also added chars_tiny table for testing CHAR(N) and VARCHAR(N).

Change-Id: If5d5db30afa4b00cf03c68c6a845f182970329f4
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/4415
Reviewed-by: Victor Bittorf <victor.bittorf@cloudera.com>
Tested-by: jenkins