implement pinpoint update for meta_data fields in redis

refs #36, refs #39
- Method 'clear_variability' renamed to 'clear_modified'.
- Redis server updates only updated data, if you change the metadata,
  not all of the metadata.
- Change the 'completed' attribute sets 'failed' to 0,
  the change 'failed' sets 'completed' to 0.
  The attributes 'completed' and 'failed' are mutually exclusive.
- Method 'update_job' accesses the Redis server only if there is data to update.

- Fixed version number.
- Clarifies the test t/01_JobQueue/16_utf8.t .
- The documentation clarified working with Unicode.

- Reformatting documentation.

- $@ is localized before we attempt to catch an exception.

Change-Id: I58e7c3c8475715eacaf66ae8adee00e543f05117