Add API reference for 0.18.

Add changelog entry for 0.17.

Add changelog entry for 0.16.1.

README: Update state of session, toolbar and firefox accounts compone…

…nts.

Add changelog entry for 0.15

Update CHANGELOG for 0.14 release.

Fix artifact ids of concept-tabstray and browser-tabstray modules.

Add changelog entry for 0.12

Add changelog entry for 0.11

Add changelog entry for 0.10