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.
Fix duplicate test case name
Remove trailing whitespace
Merge pull request #1754 from gregkare/duplicate_testcase

Fix duplicate test case name
Update history to reflect merge of #1754
Pagination generator should have :lowest priority
Merge pull request #1759 from mojombo/pagination-lowest-priority

Pagination generator should have :lowest priority
Update history to reflect merge of #1759
Prep for the 1.3.1 release
Release 1.3.1
Update the gemspec with the release post
fix wrong case for a word
Parse TOML or YAML in Jekyll::Configuration.
Better config file parser error if it's not there.
Give that LoadError a good message.
require the TOML gem, idiot.
Add some unit tests for TOML integration.