Fix link to user profile, update based on adjusted MentionPattern

The User member of a message is not needed anymore.

The from that is send to the server, should always be the "system" from. This is also called the Bounce address http://en.wikipedia.org/wiki/Bounce_address

This lines got committed by accident. They do actually nothing, as SplitHostPort will give an error if port is not given.

The SendMail function is rewritten and has the following new functionality:
 - It is optional to skip verification of keys. The config option SKIP_VERIFY is added
 - If the port is 465, or ending on 465, the TLS(/SSL) connection is started first.

All basics are implemented. Missing are the right (localized) strings
and the page markup could have a look at by a frontend guy.

- POST /user/repos
- POST /org/:org/repos

Correction for #723
Bug was : decode failed if the password contains ```:```

Related to #700

In the original bug report it was referencing only the sytem avatar images for setup users (like in the header); however the problem also persists with things like commit history.

This commit fixes the `tool.AvatarLink` function so that it also uses the already existing `avatar.HashEmail` function.

I also refactored the `tool.AvatarLink` method some to make the control flow more apparent and adhere better to DRY (there were multiple calls to the `EncodeMd5` function that the `HashEmail` function call replaced, now there is only one.)

According to the [Gravatar API](https://en.gravatar.com/site/implement/hash/) whitespace should also be removed from the email, it was not doing this previously.

Not enough arguments in call to c.AddFunc when I copied and pasted