ENH: Add `--config` option to supersed some or all of the options

[kikocorreoso]

Add a new --config option to the command line in order to avoid the repetitive use of some of the ther options. For instance, instead of this:

python -m jupy2wp.jupy2wp --xmlrpc-url http://pybonacci.org/xmlrpc.php --user kiko --password 1_2_oh_my_god!!! --nb 'dummy.ipynb' --title 'The best post ever' --categories articles tutorials --tags strawberry lucy jupyter --template basicx

Replace some of the options with a config.py including hardcoded options that are not expected to change for a user like --xmlrpc'',--user,--password,--template` so yu can use something like:

python -m jupy2wp.jupy2wp --config /path/to/config.py --nb 'dummy.ipynb' --title 'The best post ever' --categories articles tutorials --tags strawberry lucy jupyter

Hint: http://stackoverflow.com/questions/301134/dynamic-module-import-in-python/301146#301146

[astrojuanlu]

Instead of config.py one could use this:

https://docs.python.org/3.5/library/configparser.html