metatag 7.x-1.14

This fixes some bugs and adds support for the new twitter:image:alt meta tag.

Full changelog since v7.x-1.13:

• By DamienMcKenna: Corrected return code from update 7107.
• #2664624 by DamienMcKenna: Added a space in front of the Google Plus schemaorg variable to avoid HTML validation errors because of the lack of space.
• #2658902 by DamienMcKenna, swentel: Renamed the 'Add a Metatag default' link to match the D8 wording.
• #2665206 by DamienMcKenna: Don't add an index in 7029 if it already exists.
• #2670842 by Ambient.Impact: Fixed permissions in the Importer submodule.
• #2613598 by DamienMcKenna: Removed the Contributor Covenant, replaced it with a link to https://www.drupal.org/dcoc.
• #2692933 by doostinharrell, DamienMcKenna: $metatags variable in metatag_field_attach_form() may not be an array in certain circumstances.
• #2658808 by tommik: Rewrote query in update 7040 so it works better.
• #2688963 by DamienMcKenna: Added a note about the Yoast SEO module.
• #2687847 by DamienMcKenna: Added a note about the Parse.ly module.
• #2696445 by Simon Georges: Added the twitter:image:alt meta tag.
• #2678896 by Dave Reid: Fixed double-encoding of form fields.
• #2667214 by DamienMcKenna: Improved tests for string encoding.
• #2667214 by joelstein, DamienMcKenna: Decode HTML entities prior to rendering meta tags.