stripping port information from Discourse.BaseUrl

Port information if presented in Discourse.BaseUrl may break user avatar URL in the template generation.

https://github.com/discourse/discourse/edit/master/app/assets/javascripts/discourse/models/user.js
avatarTemplate()

In the future there should be a way to reference baseUrl with or without port information
Merge pull request #2791 from lidlanca/patch-1

stripping port information from Discourse.BaseUrl