rspec-system 2 helpers

Convert all helpers to use the rspec-system 2 helper format. This provides
the 'helper as a subject' syntactical sugar.

Signed-off-by: Ken Barber <ken@bob.sh>
Merge pull request #9 from kbarber/rspec-system-2

rspec-system 2 helpers
Release 2.0.0

Signed-off-by: Ken Barber <ken@bob.sh>