Restored spam prevention

closes #3128
- added spam prevention middleware
- restored tests
Prevent loading setup screen if already setup

Closes #3145
- Prevent navigation to the setup screen if Ghost setup
  has previously been completed.
- Fix templates that were incorrectly using foreach instead of each.
- Add validation for minimum password length.
- Fix up functional tests and split out tests for setup to a separate
  instance of casper because setup requires a new database.
- Add a cleanDatabase task to grunt which resets the database to
  new.
Merge pull request #3280 from jaswilli/issue-3145

Prevent loading setup screen if already setup
Merge pull request #3282 from sebgie/issue#3128

Restore spam prevention
Turn off autocomplete for user profile form

Closes #3271