update raco submodule
put up a warning when the user isn't using Chrome

fix #178
@domoritz' suggested fixes
remove unused jumbotron css
make phytoplankton demo use smaller data

Seconds, rather than minutes
vain attempt to get travis to work with google app engine again

Something is busted in Travis. I'm following this patch:

https://github.com/raphaelcuba/fbsdk-webapp2/commit/99bf7fd93b1808bf81b95244c99744073d37e9f0
switch GAE version to 1.81, the web standard
Merge pull request #180 from uwescience/detect-chrome

Detect chrome, warn if other browsers