Julia 0.3.4 update and packages precompiled into custom system image 

This updates Julia version to 0.3.4 and also provides a system image with some packages precompiled into it for faster loading.

Currently only `Gadfly` is precompiled (which also pulls in quite a few other useful packages along as dependencies).

When this version gets applied on to juliabox.org, all users would by default be set to use the system image with precompiled packages. Users may switch back to the default system image from the JuliaBox settings tab.

Also present in the PR are a couple of miscellaneous changes:
- bind zmq socket to internal ip only for security
- updates to default package bundle are applied to test cluster by default to prevent inadvertently applying untested stuff to live cluster.