Fixing import bug, reducing queries for teachers.
Cache the own_device, to avoid (innumerable) queries for this object (which, after install, never changes)
flip logic on homepage redirect
Cache computation of flat topic tree; cache Django response for flat topic tree (saves ~66% of response time)
Merge pull request #826 from bcipolli/cached_search_tree

Cache computation of flat topic tree and Django response
two small benchmark fixups
Merge pull request #827 from gimick/benchmark_tweaks_2

two small benchmark fixups
Set a max # of results, to avoid churn on the server.  Configurable (but not currently exposed)
Merge pull request #829 from bcipolli/limit_backend_search

Set a max # of results, to avoid churn on the server.  Configurable (but not currently exposed)
Fixes to integrate with newest version of khan-exercises.
Hide related videos on exercises when video isn't available.
Added version 1.9.1 of jQuery to support new khan-exercises.
Updated khan-exercises to newest version.
small regression fixes for benchmark
Correct path to raphael.js on knowledge map.
Updated Khan API data via khanload, after removing exercise blacklist.
[Issue #391] prevent user from entering negative user counts
When normalizing the knowledge map layout, avoid flipping coords twice.
Merge pull request #835 from aronasorman/issue_391

[Issue #391] prevent user from entering negative user counts
Merge pull request #821 from bcipolli/cache_own_device

Cache the own_device, to avoid (innumerable) queries for this object