pushy removal

This gigantic pull request removes Pushy from ceph-deploy in favor of remoto/execnet, temporarily skips a few good tests, removes a few bad tests and improves the overall stability by adding a global timeout for remote commands of 300 seconds, keeping a few granular ones to 7 seconds (specially the ones that start scripts).

It bumps the required version of remoto to 0.0.6 and also removes the pushy requirement from the debian, spec, and setup.py files.