Enable cli for humanization cdr grafting

[mbestipa]

I would like to run the tool using the cli instead of the web browser. Specifically, I saw that running the humanization using cdr grafting is not an option currently. Is this a feature you would be interested in having?
I'm happy to work on implementing this, I would propose a two step process:

1. Set up the cdr grafting with as minimal changes as possible
2. Make an api for the calls that are made. Currently things between the cli and the web use very similar functions for the same features in the browser and in the cli. The functions should probably be structured in a way where both of them use the same methods, but have the web interface and the cli use different methods for parsing/(de)serialising input and output. This second point would be a lot of restructuring work, but would allow the two interfaces to stay in sink more easily.