Add Node.js 0.12 stable to CI build
Add Node.js 0.12 stable to CI build

Replaces 0.11 unstable

dtest/sharp,lovell/sharp,pporada-gl/sharp,papandreou/sharp,cmtt/sharp,mdimitrov/sharp,mhirsch/sharp,mcanthony/sharp,mcanthony/sharp,mcanthony/sharp,pporada-gl/sharp,philip8728/sharp,cmtt/sharp,dtest/sharp,lovell/sharp,leiyangyou/sharp,lovell/sharp,dtest/sharp,digital-flowers/sharp-win32,digital-flowers/sharp-win32,brandonaaron/sharp,mdimitrov/sharp,brandonaaron/sharp,chrisriley/sharp,leiyangyou/sharp,leiyangyou/sharp,mhirsch/sharp,dtest/sharp,brandonaaron/sharp,digital-flowers/sharp-win32,papandreou/sharp,chrisriley/sharp,chrisriley/sharp,digital-flowers/sharp-win32,lovell/sharp,chrisriley/sharp,brandonaaron/sharp,chrisriley/sharp,pporada-gl/sharp,leiyangyou/sharp,mhirsch/sharp,mhirsch/sharp,digital-flowers/sharp-win32,cmtt/sharp,papandreou/sharp,leiyangyou/sharp,mcanthony/sharp,papandreou/sharp,dtest/sharp,philip8728/sharp,philip8728/sharp,mdimitrov/sharp,brandonaaron/sharp,digital-flowers/sharp-win32,pporada-gl/sharp,cmtt/sharp,papandreou/sharp,lovell/sharp,philip8728/sharp,mdimitrov/sharp,pporada-gl/sharp,digital-flowers/sharp-win32,philip8728/sharp,mcanthony/sharp,lovell/sharp,mdimitrov/sharp