Before the arguments weren't valid.

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>

Reviewed-by: ultrotter

To my knowledge they're used nowhere and it's at least slightly
confusing to people adding new QA checks.

Reviewed-by: ultrotter

qa_node.py: Fix typo in message
cmdlib.py: Don't add readded node to node list
ganeti-qa.py: Make sure readd isn't done for master node

Reviewed-by: iustinp

This allows us to readd a node after it failed and required a
reinstallation or replacement.

Reviewed-by: iustinp

Reviewed-by: iustinp

- When line wrapping is needed, move spaces to the next line.
- Remove embedded line breaks from error messages.

Reviewed-by: schreiberal

Reviewed-by: schreiberal

- Split main() function into several small ones.
- Current work on disk failure tests. This is not yet finished.
- Fix small typo in qa_node.py.

Reviewed-by: schreiberal

Reviewed-by: iustinp

Reviewed-by: schreiberal

Reviewed-by: iustinp