Correct verb tense.

The noun is plural ("practices"). The verb should match ("come").
Update changelog
learn.template.json: correct indendation.
learn.template.json: update G+ boilerplate
learn.json: update Dart overview
learn.json: add Polymer on StackOverflow
learn.json: s/StackOverflow/Stack Overflow
Revisions to homepage for 1.3 release.
Test
2
Add detect script
Set circle node version