Separate "primitive" and ncurses viewer from AvidaCore

[ruppmatt]

AvidaEd (all flavors) and experimental work with Emscripten have their code stored in a separate directory (apps/) from the "avida-core/" code. In general, I think it'd be a good idea to keep the code responsible for a particular interface and driver of Avida separate from its core library. Currently only the ncurses viewer, the "experimental" viewer (non-functioning?) code, and the "primitive" driver code are kept alongside the core library code.