This reverts commit f5b9ed4f.

REASON: Translation work can not be done in the docrails repository

Change the default test locations to avoid confusion around the common
testing terms "unit" and "functional".
Add new rake tasks for the new locations, while maintaining backwards
compatibility with the old rake tasks.

New testing locations are as follows:

    app/models -> test/models (was test/units)
    app/helpers -> test/helpers (was test/units/helpers)
    app/controllers -> test/controllers (was test/functional)
    app/mailers -> test/mailers (was test/functional)

[ci skip]

Fixed second assert_match - previous one didn't make any sense (if the first passed, the second passed as well)

It's better to pass strings to assert_match - it converts them to regular expressions, escaping special chars like '.'. It seems email.encoded contains some unexpected line breaks (due to encoding), it's better to assert_match email.body.to_s.

Use proc as default argument to recaculate recipients array every time

for "assert /" warnings.
Removed because if somebody will use this code
they will get warnings!

* Changed the lines that said <tt>config/environments/env.rb</tt> to <tt>config/environments/$RAILS_ENV.rb</tt>.  People were mis-interpreting the filename to literally be env.rb.

Action Mailer guide update: the :to parameter now supports both String and Array values to indicate recipients.

Action Mailer Basics Guide: Added example on using mail(:template_path => ..., :template_name => ...) to specify custom template files.