Add empty 'scrape' command (the beginning of work on h2s/ppl#23)
Add the mail gem
Implement the simplest possible form of a "scrape" command for h2s/ppl#23

This isn't done yet. It's not been tested thoroughly enough to release, and it
still has a few bits of missing functionality.

- It needs to autogenerate a contact ID based on their display_name
- It needs to not trip over and die if any of the properties it depends on
  aren't present

I'm thinking this might actually be another prime candidate for a Ppl::Adapter
mail-scraping interface.
Create Ppl::Adapter::EmailScraper
Add Ppl::Adapter::EmailScraper::Mail
Make the email scraper adapter return an array
Move the existing scraping code into place in the email_scraper adapter
Refactor the email sender scraping into its own method
Add contact ID generation based on their name
Generate a contact's ID from their email address if necessary when scraping
Add the scrape command to the dependency injection container
Add scrape to the command suite
Read stdin the Ruby way for email scraping
Scrape contacts from stdin in the scrape command
Inject an email_scraper into the scrape command
Fix an awkward issue with ARGF in a slightly hacky way

Ruby's ARFG is complaining because the "scrape" subcommand isn't a real file or
directory. This just kicks that out of the ARGV list to get on with the
processing.
Save all scraped contacts
Only save the contact if the user approves
Don't bother the user in quiet mode
The refactoring begins