add a timeout to zk check (fixes DataDog#310)

Exception.message doesn't work in python 2.4 (closes DataDog#320)

The old tab v. space story

Passes travis checks.

Fixed incorrect tests

Fix RPM restarts on upgrades.

This won't appear to be fixed until two releases from now, since
the bug is in the prerm step of agents already in the field.
After than all should be well.

Fixes DataDog#250.