Improve bash escape code #31

It seems it's possible to execute arbitrary bash commands through HTTP parameters when using bash services ( and other possible languages too ).

This isn't intended behavior and should be fixed.

The actual security implications would be determined by the configuration of the server environment microcule is running on. For hook.io, it's not really a problem ( since workers running code are secure on the operating system level ), but it could cause issues for on non-secure systems running untrusted source code.