Add a directory option "-d" for createcaslibjson.py

[AllanWTham]

Hi there,

Would you be able to add an option "-d" to allow users to specify the output directory name to contain the json files?
Currently, the default behaviour is that it creates a "caslibs" directory in the local directory.

[tomstarr]

Hi Allan, this will be no problem at all, and I can implement this once I return from paternity leave (in Feb).