Added Phing

At my point of view the most powerful PHP project build system
+1 Raspberry Pi & GPIO related lib
Fixed PHPSpec link

Repository moved.
Merge pull request #33 from gitetsu/patch-1

Fixed PHPSpec link
Add PHPCI (suggestion by @Kristories).
Add RedBean (suggestion by @Leimi).
Add F3.
Add Flysystem.
Add APIGen.
Add Twitter OAuth and REST.
Add Dropbox PHP SDK.
Category description tweak.
Typo.
Rename books category and added new books.
Add PHP RFCs page.
Tweak HgInit description.
Add Beyond reading series.
Add create your own framework series.
Add HTML5Rocks and MDN.
Cleanup spacing.