link 7.x-1.4

Issue #2470377 by rhclayto: Adding a class with underscores, the class gets rendered with hyphens
Issue #609560 by Boobaa: Provide token for hostname
Issue #2632728 Apply patch: link-field_link_validate_overrites_langcode-2632728.patch
Issue #2247261 by heddn, sumitmadan: URLs are not validated
Issue #2513706 by rrfegade: Spelling errors in D7
Issue #2470968: Add README.txt
Issue #2055111 by joelpittet, mikeytown2: skip over re-loading entities for tokens in link field attributes unless there's a token to process.
Issue #2367069 by jcfiala:Fixed entity_token for link after node_view was called.
Added setup function to LinkValidateUrlLight to enable link module, which was failing drupal.org qa testbot.
Issue #2364673 by jcfiala: Replaced drupal_html_class() with drupal_clean_css_identifier() so that link field classes are not forced to lower case.
Added tests to test entity_token token with link.