Remove built-in commands (i.e. check and build)

[nvs]

This is a big breaking change. However, Map will shift towards providing libraries only. This should resolve #18 and #89 by making them redundant.

Removal of the commands is simple. However, the 'testing' suite (i.e. Gem) would need to be updated. Basically shifting much of the command behavior from Map to Gem. Naturally, using Map should be a nice experience. So attention needs to be given to revamping the libraries to be more user friendly and consistent.