Update installer image for Wikimania 2014

* VirtualBox 4.3.12
* Vagrant 1.6.3
* Vagrant-VBGuest 0.10.0
* Ubuntu 14.04
* Pre-populated apt and composer caches
* Update README for new setup.{sh,bat} install method

Change-Id: I21f459aec3d585bef1987b1da1cf597684212d87
Merge "Update installer image for Wikimania 2014"