Update pry-debugger, debugger
Add handling for zeus
Add Procfile.dev that includes zeus
Document zeus usage in README
wip: Add fields to agreement

* Failing spec
Create Field and AgreementField models
Relaxed the uniqueness validation so we can update existing agreements.
Add columns fields.enabled_by_default, agreement_fields.enabled
Provide default fields in db:seeds.  Use in tests.
Agreement accepts nested agreement_fields
Fix routes to allow both repo names with periods as well as .csv format.

* Consider paths:

  /agreements/jasonm/beerfire.com
  /agreements/jasonm/beerfire.com.csv
Agreement can #build_default_fields, supersedes #create_default_fields
Specify fields when creating an Agreement
Zeus is broken, le sigh.  Wish it would ever work.
Accept configurable fields for agreements
Consistently order agreement fields and field entries
Add Field#description.  Add "Corporate Contributor Information" field.