Hints for claws-mail in main

Hints

• asv-developer-name-tag-deprecated
  org.claws_mail.Claws-Mail.appdata.xml:8 -
  The toplevel `developer_name` element is deprecated. Please use the `name` element in a `developer` block instead.
• asv-description-first-para-too-short
  org.claws_mail.Claws-Mail.appdata.xml:13 - Claws Mail is an email client (and news reader), based on GTK+, featuring:
  The first `description/p` paragraph of this component might be too short (< 80 characters). Please consider starting with a longer paragraph to improve how the description looks like in software centers and to provide more detailed information on this component immediately in the first paragraph.
• asv-content-rating-missing
  org.claws_mail.Claws-Mail.appdata.xml -
  This component has no `content_rating` tag to provide age rating information. You can generate the tag data online by answering a few questions at https://hughsie.github.io/oars/
• asv-developer-info-missing
  org.claws_mail.Claws-Mail.appdata.xml -
  This component contains no `developer` element with information about its author.