Various cleanups to Ubuntu installation instructions:

* Avoid editing /etc/apt/sources.list add nginx repo, instead create
  /etc/apt/sources.list.d/nginx.list

* Avoid editing /etc/nginx/nginx.conf, instead put server_name_hash_buckets
  setting into discourse.conf

* Proper-case Discourse when it is referring to the product name, so that all
  the lowercase references are to the user created during the installation
Address @Supermathie's concerns in PR1430
Delegate :username rather than using a class method.

This is just a little cleaner?
Trust level 3 users can edit topic titles and change category
Sanitize your bio after you save it and render it to yourself.
Version bump to v0.9.8.2
Topics Entered -> Topics Visited
whoops, I meant "Topics Viewed"
Updated Ukrainian translation
Added faq.uk.html.erb (copied from English version)
Merge branch 'master' of https://github.com/Maximaximum/discourse
minor /top copyedit
another minor /top copyedit
BUGFIX: do not install dependencies from plugin, must be explicit
FEATURE: script/discourse import AND export
BUGFIX: export was broken, not exporting any tables
Added Ukrainian FAQ translation (full).
BUGFIX: support nil params
fix for nil session in mobile_detection.rb
DIEEEE SOFTWARE.MD DIEEEEeeEE