combination of 8 commits.
piwik: add event tracking

add tests

piwik: fix brackets in test

piwik fix tests

value fallback to revenue

add comma

fix tests

finalize tests
added fix for createdAt and created for group method, along with tests
Merge pull request #446 from segmentio/fix/piwik

 combination of 8 commits.
Merge pull request #449 from segmentio/fix/intercom

added fix for createdAt and created for group method, along with tests
Merge pull request #447 from cibot/master

Integration with getblueshift.com
blueshift: removing single quotes
Amplitude: added setDomain and setGlobalUserProperties to init
Merge pull request #450 from segmentio/fix/amplitude

Amplitude: added setDomain and setGlobalUserProperties to init
Release 1.3.6
remove parens from campaign params
Merge pull request #453 from segmentio/fix/ga

remove parens from campaign params
Release 1.3.7
deps: bump utm-params
Release 1.3.8
remove errant parens
fix amplitude campaign name
Merge pull request #457 from segmentio/fix/ga

remove errant parens
Release 1.3.9
added createdAt as a format in customerio
Update `yields/store` to 1.0.1