Merge branch 'github.com/master'

Conflicts:
	tasks/assemble.js
	test/actual/multi/dest1/helpers.html
	test/actual/multi/dest1/helpers.md
	test/actual/multi/dest1/html-helpers.html
	test/actual/multi/dest1/html-helpers.md
	test/actual/multi/dest2/sub-dest/helpers.html
	test/actual/multi/dest2/sub-dest/html-helpers.html
	test/actual/nested-layouts/helpers.html
	test/actual/paths/helpers.html
	test/actual/paths/html-helpers.html
	test/actual/yfm/associative-arrays.html
	test/actual/yfm/block-literals.html
	test/actual/yfm/document.html
	test/actual/yfm/lists.html
	test/actual/yfm/variables.html
add time-grunt for reporting elapsed execution time of grunt tasks.