Move reverse trigger code to maintain alphabetical order
Make quotes and braces consistent with the rest of the code
Make the reverse trigger better match jenkins-job-builder's names

The option keys are thus `jobs:` and `result:` instead of `watch_projects:`
and `trigger_on:`.
Add an endToEnd acceptance test for the reverse trigger
Clean up documentation for reverse trigger
Add to the Contributing section in the README
Bump version to 0.7.0