Update Profiler.php to show HTTP_DNT status

show do not track header status
Fix #2498
Update library documentation and changelog
Merge pull request #2497 from yazuu/upload

Upload : change the file extension to lower case
Issue #2508
Changed the smiley zip file download to reflect the new location at the
ellislab.com domain from the codeigniter.com domain.
Merge pull request #2511 from stevencrothers/develop

Changed the smiley zip file download to reflect the new location at the
[ci skip] Alter a link in the changelog
The script is halted and a '500 Internal Server Error' is issued when a fatal error occurs.

Signed-off-by: Jesse van Assen <jesse.v.assen@gmail.com>
Optimize Change Log, add entry for 2.1.4
Upgrade notes for 2.1.4
Update Downloads page

Even though it's useless right now...
Update GitHub "tags" link to new Releases feature.
PHPUnit & Travis failures due to new version of vfsStream.
Merge pull request #2526 from cryode/bug/vfsstream

Fix PHPUnit & Travis failures due to new version of vfsStream.
Fix Travis tests
Fixing incorect references for time zones
Merge pull request #2530 from AdwinTrave/develop

Fixing incorrect references for time zones in documentation
2.1.4 release related stuff
[ci skip] Add 2.1.4 upgrade instructions page