Removes aliases that make common congress_member instance methods
into class methods.  I wonder why those seemed useful.

* shorten long lines
* move single-use method into the only place it's used

    * DRY up last_response_json
    * use `let` to create instance methods
    * use string interpolation instead of `'' + foo.to_s`

* break the crazy-long execute method into smaller methods
* move some code that doesn't pertain to the model out of the model
* fewer nested if statements
* put `extends` calls and ActiveRecord methods at the top of the file
* don't pass the CongressMember, the record already knows its CongressMember.

* remove unused `fill_out_form!` method
* shallower if statments
* move code into named methods

Split the giant factories.rb into smaller, single-model factories.

Move the list into a constant that the wider app can rely on

* Everything is a class method; use class << self instead of declaring
individually
* Remove unused methods

Smaller, more focused files are more legible than larger ones.

* delegate to a named scope in CongressMemberAction
* use new hash syntax

Now it will be easy to swap out PhantomJS with something else!
* the CongressMemberAction model doesn't need to know about Capybara,
* move screenshot methods into their own file

Pull the logic into a tidy lib class

* code style consistency
* DRY up repeated logic
* keep constants in one place
* more expressive names

* DRY up repeated logic
* use .map instead of instantiating and pushing to an ary
* fix some typos