Update lables in app setup/edit dialogue: main.xml

* Added to not use special characters (beyond space and hyphen) in site name
* Added how multiple host namesd (eg www *and* non www) can be added with example
* Updated description of where to edit hosts from old <0.6 layout (ie settings > networking > hosts instead of network > hosts)
* Replaced some jargon (DNS resolvable) with something still a bit jargonish but more commonly understood
* Mentioned in the edit dialogue that the default may be 443 if using SSL (it could be confusing if they apply an ssl, come back and the default port number there isn't 80). I didn't add this to the setup dialogue as when apps are first set up they're not using SSL, so they will always be 80.
Merge pull request #450 from Bugsbane/master

Update lables in app setup/edit dialogue: main.xml