Bundle exec should be used
Align bundler instructions based on @hunner's previous patch

This modifies the README.md file to align the usage instructions for bundler
so --path switches are the same, and recommended Jenkins scripts are the same.

Signed-off-by: Ken Barber <ken@bob.sh>
Merge branch 'bundle_exec'

* bundle_exec:
  Align bundler instructions based on @hunner's previous patch
  Bundle exec should be used