Merge pull request #8 from ClojureBridge/master

Bring curriculum up to date from main ClojureBridge repo
fixing commented solution value 3.0 => 9.0
Merge pull request #11 from rebekah/master

fixing commented solution value 3.0 => 9.0
Updated OSX lein install instructions
Merge pull request #12 from clojurebridge-sf/rw/update_osx_setup

Updated OSX lein install instructions
clarify truthiness

Everything besides `false` and `nil` is truthy (logical true) but not `true`. E.g. `(true? :foo) -> false`.
Merge pull request #13 from maxcountryman/patch-1

clarify truthiness
Merge pull request #113 from clojurebridge-sf/master

Some minor changes based on how the SF workshop ran for everyone to review