Merge branch 'release/0.2.0' into develop
Aggregators compose. This adds the methods.
remove cast
Merge pull request #192 from twitter/feature/remove_cast

Remove Cast from Trampoline Implementation
Fixed bug in QTreeTest
add mailing list
add archive link.
fix mailing list
Added code + test to combine tuple of aggregators into one aggregator.
FlagMonoid
OrValMonoid and AndValMonoid
simpler AndValMonoid
Merge pull request #198 from mikegagnon/flag_monoid

FlagMonoid performs logical OR
stash
ScMapMonoid
avoid instanceOf
refactor
tests for ScMap algebras
change val to def
Merge pull request #196 from twitter/feature/mailing_list

Add Community Section to README.md