Update security.php to check for presence of a few new files.

Those being README.md, CONTRIBUTING.md, .travis.yml and composer.json.
Update version number to new release
Clarify workflow for 3rd party vs core team.
Rename readme to uppercase
Eat cookies that were set from JS upon logout. Fixes #352
Add empty robots.txt fixes #351
fixes #358

Problem: Unable to edit files ending with `.html` extension in File Manager

Workaround: For files ending with URL suffix - add `has_url_suffix=1` to $_GET and detect it while editing those files.
fixes #358

Problem: Unable to edit files ending with `.html` extension in File Manager

Workaround: For files ending with URL suffix - add `has_url_suffix=1` to $_GET and detect it while editing those files.
fixes #418

Prevent non-administrators from setting "is_protected" of page.
Add default CRLF/LF setting to repo to force use of LF for devs.
fixes #463 - Snippet add/delete/edit permissions
fix edit redirect url
UI changes for snippet permissions
Avoid duplicate User->username in controller
fixes #515
Remove Windows line endings in favor of Unix
Fix Gravatar helper's lack of input validation
Make travis less verbose; notify on change only.
Add missing Persian/Iran entry to ietf array
Fix small problem in initial SQL data
Correct BackupRestore plugin's version number