rebase completion script for new commands

add 'version' subcommand
add '--status' and '--servicelevel' to 'list'

add '--serverurl' where approriate

Some general refactoring, mostly changing
options and functions to be alphabetical order.

Fix 'service-level' completion (the '-' confused
the default command->completion function lookup)
Merge pull request #578 from candlepin/alikins/completions_rebase

rebase completion script for new commands