Fixed class loader of the script engine.

The script engine didn't have the plugin class loader. Instead, it had the thread context class loader. The problem with this is that this prevents scripts from instantiating classes from other plugins to e.g. implement undo when WorldEdit is available. The thread context class loader is now set to the plugin class loader while instantiating the script engine which solves this issue.
added documentation for the bukkit object.
Update Anatomy-of-a-Plugin.md
Update YoungPersonsGuideToProgrammingMinecraft.md
Update ypgpm.md
Merge pull request #154 from pvginkel/master

Fixed class loader of the script engine.
moving bukkit.js from lib to modules (it shouldn't be part of core)
First phase of transition from Bukkit to Canary.
Some of the plugins are not yet supported.
If you're feeling brave you can build from source using ant.
fix bug in fireworks (was using wrong framework)
Added items to API docs, added recipes. added utils.players() and utils.playerNames() functions.
Fixed bug in creating signs in canarymod and updated minigames/scoreboard to work with example code from book.
reinstating bukkit as build target.
moving path.
Added utils.worlds() and utils.stat. enums
Get build working on jre6,7,8
Update .travis.yml
Make events and items work with JRE 6, 7 and 8
Merge branch 'master' of github.com:walterhiggins/ScriptCraft
Adding create() function for recipes - creates but does not add (see updated listing in book chapter 16)
Update README.md