Merge examples-react-5989-3: Use task.react in twisted.names examples

Author: rwall
Reviewer: thijs, tom.prince
Fixes: #5989

 * Updated all twisted.names example scripts to use task.react, which
   shuts down the reactor reliably and logs uncaught exceptions.

 * Tidied up the output of the twisted.names example scripts. Results
   of all scripts are now neatly printed to stdout and certain
   expected errors are printed to stderr.

 * Standardized the example script --help output

 * Examples now return non-zero exit code on certain errors

 * Added some new unit tests for the twisted.names examples - testing
   for consistent usage and error messages and for a standard shebang
   line.

git-svn-id: svn://svn.twistedmatrix.com/svn/Twisted/trunk@37878 bbbe8e31-12d6-0310-92fd-ac37d47ddeeb