Don't compile CSS on request

- Add new flag "stylesheet_needs_recompile"
- Use old CSS file until the stylesheet is recompiled and the flag is
  set to _false_
Merge pull request #327 from sharetribe/dont-compile-on-request

Don't compile CSS on request
Cucumber steps
Add automatic confirmation time to conversation
Add automatic confirmation days after
More step implementations
Refactor conversation confirmation
Refactoring: separate confirm_or_cancel
Auto confirmation mailer
Automatic confirmation after 14 days
Minor refactoring
Fix tests according to the new mail sending policy
New mail strategy: ignore last sent mail
Reminder 2 days before closing
Copy texts
Remove :number_of_sent_messages
Days to cancel
Copy texts
Minor fixes
Fix some tests