Email-validate

- Introducing an EmailAddress class, thx to reinhard-mueller
- Added a test for making sure there's a data directory with blacklist
files on install.

- Python distutils/setuptools is a mess. Fix data dir creation on
install.

- Fixed built-in datadir creation again.

- Fixed https://github.com/karolyi/py3-validate-email/issues/13

- Fixed the automatic download of the validate_email/data directory on
package install time. The source distribution MUST NOT include the
data directory, local installs have to fetch them when they are
executed.

- Added a validate_email_or_fail function that will raise an exception
(base class validate_email.exceptions.EmailValidationError) when the
passed email check fails, while logging a warning with the validation
result.
- The blacklist updater can now use a separate thread and writable temp
paths to download and store its data, while logs about the update
process on DEBUG.
- Exposed a `validate_email.updater.update_builtin_blacklist` to update
the built-in blacklists while running.