Replace absolute (personal) paths to relative project paths

There are problems building the project on different computers because the code is littered with lots of absolute paths, e.g.

`C:\\Users\\Daniel\\AndroidStudioProjects\\KitchenAssist\\` **...**

These need to be made to be relative paths using environment variables such as `$PROJECT_DIR$`

This was probably the result of committing configuration files that should not have been staged. Make sure only to commit source that has been revised.