substitutions as a separate option for surveys are gone, closes #24, because it is now possible to dynamically evaluate knitr mixed with markdown for survey item and choice labels
also switched pause and time branch to R, am not happy with how they deal with missing values yet, should probably switch the entire time logic to R when we have time, closes #2

also changed the schema to pave the way to fixing these issues #3, #1

I am closing #15 for now, because it was fairly easy to support figure attachments in emails using a custom image upload function in knitr (closes #25)

some other cleanup as well
Merge branch 'develop' of https://github.com/rubenarslan/formr into develop

Conflicts:
	documentation/Example files/all_widgets.xls