Update Monolog to 1.7
Allow custom email classes that extend `CakeEmail`.

Using the `Email.classname` configure key, it is now possible to
use a custom email class as long as it extends `CakeEmail`.

For example, you might have an `AppEmail` class you need to use,
just add the following to `bootstrap.php` and you're done:

    Configure::write('Email.classname', 'AppEmail');
Add travis support.
Bump version to 1.4.2.
Merge branch 'release/1.4.2'