notyourface is explicitly meant as an Open Source project that is open for community contributions. You are welcome to open Pull Requests with bug fixes or feature implementations as long as you are the sole author of the code you contribute and you agree to publish it as part of the notyourface codebase, licensed under the MIT license.
That being said, to keep you from doing superfluous work, please open an issue describing a bug or feature idea and discuss the matter with a the maintainer before you start working on things ♥