Sort plugins so people can have "load orders".

This allows for people to do something like "_plugins/1-autoload-global.rb" and have it load first and so on making it much easier to organize code and have a "header file" that does all the requiring up front if it's needed for all plugins.
A start at a gem-based plugin whitelist for Pages.
Add --whitelist flag and internal logic
Remove Site.whitelist attribute.
Replace yoursite.com by example.com
Revert hint
Revert stupid whitespace
Example FTW
For issue #1714: Add documentation for post_url when posts are in subdirectory
Remove extra trailing whitespace
Update link to example Rakefile to point to specific commit.

The link was pointing to the latest version of the file which had been changed and no longer provided the intended example.
Merge pull request #1741 from andrewhavens/patch-1

Update link to example Rakefile to point to specific commit.
Update history to reflect merge of #1741
output including file for include tag error
restrict rescue-clause in IncludeTag#render

As it previously enclosed the whole method, it also
wrapped file validation errors, which is not meant to be.

Fixes #1745.
Merge pull request #1718 from thomasdao/master

Add docs for post_url when posts are in subdirectory
Update history to reflect merge of #1718
Merge pull request #1736 from gregkare/trailing_whitespace

Remove extra trailing whitespace
Update history to reflect merge of #1736
Merge pull request #1746 from maul-esel/missing-include

output including file for include tag error