Avatar not displayed when username contains a dot

[rdenarie]

When users have usernames with a dot (like r.denarie), the avatar is not displayed in chat application.
In eXo, the url used for the avatar is : /rest/jcr/repository/social/production/soc%3Aproviders/soc%3Aorganization/soc%3Atest%2502test/soc%3Aprofile/soc%3Aavatar
In chat, the url used is /rest/jcr/repository/social/production/soc:providers/soc:organization/soc:test.test/soc:profile/soc:avatar, which throws a 404 error. So the default avatar is displayed

We should escape characters not accepted by JCR.