adding 2.21 changelog and updating dates in 2.2
Merge branch 'zp-changelog' of github.com:plaid/support into zp-changelog
changelog additions and revisions
minor updates to 2.21 changelog
updated error codes
minor updates to 2.21 changelog
minor updates to 2.21 changelog
minor institutions update
updating names and dates
Merge pull request #19 from plaid/zp-changelog

Changelog 2.2.1 creation and 2.2.0 name changes