use cloned document for measurements
Merge branch 'master' of https://github.com/niklasvh/html2canvas

Conflicts:
	build/html2canvas.min.js
	dist/html2canvas.js
	src/core.js
Begin implementing cross-origin iframes
Merge branch 'fix-doc-measurements' of https://github.com/ddrscott/html2canvas into ddrscott-fix-doc-measurements

Conflicts:
	dist/html2canvas.js
	dist/html2canvas.min.js
	src/core.js
Merge branch 'ddrscott-fix-doc-measurements'
Use correct window size for cloned iframe
Revert back to grunt-contrib-connect
Fix missing jsonp feature with grunt-contrib-connect
Fallback to jsonp proxy if browser doesn't support cors xhr/image