cli args
wip: attempt to include template as data
package markdown template

Had to do some temp file wrangling to make an exporter with an
absolutely pathed template file.
require all ipython
doc, fix missing attributes
only require ipython, jinja2
implement --to --from cli args
convert un-executed notebooks
remove excess newlines from end of Rmd example
update precode arg to new block format
use a class for knitr
allow stripping outputs when writing notebooks
tidy
correct creation of metadata/outputs
update readme