Major update, read details below.

Updated the dump command build to be more generic (hopefully) and not just MySQL specific.
Provide an "db-allows-remote" site alias option so aliases can inform sql-sync-pipe that their DB allows remote connections (for Pantheon).
Now by default, tables that contain "cache" anywhere in the name will only be transferred as a structured table without any data. If you want to include the cache data, pass the --include-cache-tables option.
Better handling on when gzip is used (only when using the dump command on a remote server).