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
updated spanish translation
Create a cold age helper, make sure the first age column is strictly
`created_at`, add cold to the second column.
FIX: Suggested Topics had a hardcoded 5 and was ignoring the
SiteSetting
FEATURE: top is now by default in the top menu
fixing regression, adding max-height to #site-logo
Merge pull request #2101 from awesomerobot/master

fixing regression, adding max-height to #site-logo
PERF: Don't blur all elements on a page
add calendar icon to best of
add envelope icon to invite friends default btn
fixing the remnant borders left on the header buttons
reduce docked header title font size slightly
JSHint QUnit helpers

- Don’t redefine controller
- Mark all functions as exported
- Mark the QUnit asyncTest as a global function
JSHint parse_html.js

- Mark Tautologistics as a global
- Mark parseHTML as exported
JSHint assertions.js

Mark all functions as exported
JSHint test helpers

Remove unreferenced globals
reduce undocked header title font size slightly
JSHint i18n.js

- Mark the I18n object as an overridable global
- Normalize comma first style rather than turning on lax comma
- Add missing semicolons
- Remove unnecessary semicolons
- Fix options overloading in “lookup”
- Use strict comparison for typeof checks and remove unnecessary parens
JSHint run-qunit.js

- Turn on devel for console and phantom for the phantomjs globals
- Remove unnecessary semicolons
- Use strict comparisons
- Add missing var statements used by for…in