This change is aimed at improving the development experience.
- The option `make delete` has been added.
- Added check for `NAME` and `NAMESPACE` variables
- Now, any package (not just system ones) can include options such as
make show, make diff, make apply.
- Applications from packages/extra require explicit specification of the
`NAMESPACE`.
- Applications from packages/apps require explicit specification of both
`NAME` and `NAMESPACE`.
Signed-off-by: Andrei Kvapil <kvapss@gmail.com>
