Add daiquiri-admin and scripts for npm, build, clean

[jochenklar]

This PR ports some functionality I developed for RDMO last year over to Daiquiri. I adds an daiquiri-admin executable that can be used in any directory. Right now, I can be used for 3 things:

daiquiri-admin npm run [watch|build|build:prod]  # shortcut for nvm use and npm run ...

daiquiri-admin build  # build the front-end and then the python package

daiquiri-admin clean [all|dist|media|npm|python|static]  # removes files which are gitignored

[kimakan]

Looks good! I've tested it by building the package with daiquiri-admin build and releasing it on test.pypi (https://test.pypi.org/project/django-daiquiri/0.9.0.dev1/). The installment with pip worked wonderfully.

[jochenklar]

Glad you like it. New scripts can be added in the management/commands directories of the different daiquiri apps.