Use htmltools 0.2.1 for HTML-related tasks
Refactor dependency passing code

No need to pass dependencies around. Now dependencies are attached to
the elements that need them (basically). Delegate to htmltools package
to deal with rendering and knit_print-ing HTML.
Merge remote-tracking branch 'origin/master' into htmltools-refactor
Add shiny dependency to ggvisOutput
Tweaks from code review feedback
Import knit_print S3 methods explicitly; fix broken refactor
Use HTML escape for gear icon

Attempting to fix Windows problem with gear/controls appearance
Merge branch 'htmltools-refactor'

Conflicts:
	R/shiny_layout.R
	man/ggvis_dependencies.Rd
Bump Shiny version requirement to 0.9.1.9009