Change for Rails 4 compatibility

Clearance currently raises exceptions in Rails 4 for two reasons:
1. Generators and routing raise exceptions because they use 
```match "path"```
instead of 
```get "/path"```

2. Clearance::User validates the format of email addresses using anchors that potentially allow multiline strings to pass the format test. Rails 4 raises an exception if validates_format_of employs ^ and $ anchors rather than \A and \Z. Clearance::User#normalize_email strips away the whitespace before validation in any event, but Rails will raise an exception whenever the validation is triggered due to the perceived vulnerability.

The proposed changes to routing and email format validation pass specs and appraisals for Rails 3.0.x, 3.1.x, 3.2.x, and 4.0.0.beta. Note that the last commit (1a045f5) adds 4.0.0.beta to Appraisals, but in order to install it you have to have installed all the Rails dependencies (actionmailer, actionpack, activesupport, activerecord, activemodel, railties) 4.0.0.beta versions locally, unless there's an easier way to make Bundler fetch them on demand.