Add hibernateUrl validator

[philippd]

Add new validator for URLs using the regex used by Hibernate URL validator: http://docs.jboss.org/hibernate/validator/5.1/api/org/hibernate/validator/constraints/URL.html
This validator will be used for @url annotations when the valdr-bean-validation plugin is used for the back-end.

see #24

[marcelstoer]

Hibernate does not rely on regex but on java.net.URL (see https://hibernate.atlassian.net/browse/HV-886). This means that in order to port this to JavaScript we have 3 (or more?) options:

• port java.net.URL to JavaScript :(
• find an existing implementation of rfc 2396 in JavaScript (haven't found one yet http://www.grauw.nl/articles/resolve-uri.html) :(
• find existing and proven regex for rfc 2396 (http://regexlib.com/REDetails.aspx?regexp_id=2088, http://lists.xml.org/archives/xml-dev/200108/msg00944.html, http://geeksandgod.com/forums/web-development/php-/-mysql/validate-url-regex) :(

[marcelstoer]

Decision: we create dedicated hibernateUrl validator which will delegate to the url validator (adapted from AngularJS) for now. It'll therefore ignore the Hibernate properties protocol, host, port.