Preserve arguments when activating venv

[simonklb]

No description provided.

[johnsca]

I'm fine with this, but why would a hook have any args?

[simonklb]

This might be a very special case, but I have an action written in bash in my charm which in turn runs a python script that I want to be left running in the background (this is the script which takes an argument and also uses the activate_venv function).

Although when I come to think about it, I could probably get the options via hookenv.action_get instead of passing them as arguments to the python script. But hey, if this isn't adding any extra baggage, it might be useful for someone else.