chmod +x *.py files to match perms as set during the packaging process

[onejli]

From an earlier email chain:

I think the failure is here in the observer process (https://gist.github.com/onejli/1fa43cf2615d138d6324#file-syslog-L150) which eventually sends signal 134 (aborted) and exits 0 (https://gist.github.com/onejli/1fa43cf2615d138d6324#file-syslog-L203). Within mesos-executor, https://github.com/apache/mesos/blob/0.19.0/src/exec/exec.cpp#L299 invokes launchTask which eventually aborts https://github.com/apache/mesos/blob/0.19.0/src/launcher/executor.cpp#L192.

The command it's trying to run is here https://gist.github.com/onejli/1fa43cf2615d138d6324#file-deimos-tmp-L51. Running it on my physical host, I see where the error arises:

$ /home/mesos/deimos/deimos/__init__.py wait @@observe-docker@@ 8cdc82785820b2c167ad610913dd2486bffa147b8ac4299786bf1a9fed34312f
-su: /home/mesos/deimos/deimos/__init__.py: Permission denied

It's a perm issue. My checkout from github has u+rw (but not +x) on all *.py files. Since all the other invocations of demios by mesos are via that bin/deimos stub (which explicitly declares the python interpreter), this issue didn't come up earlier. I'm thinking it might best to change the invocation of deimos to the "proper" binary instead of __init__.py on this line https://github.com/mesosphere/deimos/blob/0.3.1/deimos/containerizer.py#L138.

This PR takes a slightly different approach than what was mentioned in my above snippet and updates the file perms to match what the packager "does" instead of using the path to the deimos binary passed to the Mesos slave (i.e. --containerizer_path=/usr/local/bin/deimos).

[solidsnack]

Please install Deimos with pip or setup.py install. It is not intended to be run any other way at present. The bin/deimos stub is there for convenience in running some basic tests locally; but note that setup.py does not reference and it isn't used in the released package.