remove unused plugins from the tuts
add text tut
merge
merge, remove unused plugins from text tut
merge from master
expand markdown and html cells in text tut
add section on sharing to main tut
add section on the start page and generally working with the web browser to the main tut
Handle moving markdown editor up and down

fixes #350

Due to the way that epic editor works and the way that moving elements
via the cellmanger you need to reinit the markdown editor to reshow the
markdown content.
expand and rewrite autotranslation tut
Merge pull request #594 from twosigma/sjs/350-markdown-bug

Handle moving markdown editor up and down
Update README.md

new screencap with new UI
Update README.md

improve layout around image, remove "beta"
Merge pull request #595 from twosigma/spot/579

more tutorial work
Prevent modal screen overflow

fixes #288