Re-add line that was removed from the Changelog

[ci skip]
Revert "Re-add line that was removed from the Changelog"

This reverts commit 79342a6e99cf6a8cfe782b9092fbf001366e9c8d.
README.md: fix 'filter!' typo
Merge pull request #436 from aspiers/master

README.md: fix 'filter!' typo
Removed outdated section about filesystem handling

Filesystem adapters are now handled by the Listen gem.

Therefore I propose to delete this entire section, since this is all handled transparently. I have created a Wiki page and moved the content there. https://github.com/guard/guard/wiki/Efficient-Filesystem-Handling
Merge pull request #438 from tilsammans/patch-1

Removed outdated section about filesystem handling [ci skip]
Fixing broken link for adding proper readline support
Merge pull request #439 from theroux/master

Fixes broken link in Readme [ci skip]
README.md: add known issues section warning about nasty symlinks bug in listen
Merge pull request #440 from aspiers/master

warn about nasty bugs in listen [ci skip]
Escape `notify-send` arguments.

I have no idea how to write a failing spec, because escaping
happens within `system` when you provide each argument
as parameter.

system([env,] command... [,options]) → true, false or nil

(Fixes #443)
Add Buildheroes webhook
Update .gitignore
Improve notification documentation. (See #446) [ci skip]
Add bundle exec guard to Installation instructions

For anyone else who’s new to Bundler. Consider adding this to Start section too.
Merge pull request #447 from oli/patch-1

Add bundle exec guard to Installation instructions [ci skip]
Fix changelog

[ci skip]
Update gem homepage (http://guardgem.org)

#427
Restructure README.

This moves some information to the wiki and changes some headings
to `h4`, so they won't appear on the guardgem.org menu.

The idea is to make the menu on the Guard homepage more slim and
focus on the important parts. Advances and rarely used stuff needs to
go to the wiki.
Fixes #453