Remove some code thanks to Forwardable
Simplify code by using guard clauses instead of if blocks

Also replace `#kind_of?` with `is_a?`
Add missing test case for nested hash
Replace more if blocks with guard clauses
Remove local variable
Simplify the knife runners by using a mixin
Ignore deps blocks from coverage

This is handled by knife
Move item to a local variable
Add initial specs for the knife commands