`pip install backgroundchanger` doesn't automatically install dependencies.

[evantkchong]

Hi, I noticed that installing this package via the command pip install backgroundchanger doesn't automatically install the dependcies required for it to run (ie. requests and pywal). This seems to be due to a missing install_requires argument in setup.py. I'm currently working on a fix that involves modifying the relative imports in __init__.py so that we can access the config variables from config.py without encountering import errors caused by the relative imports. I will link this issue when a PR is ready.