fix(avatars): load profile image on settings and sign in pages if available

Fixes #1727

Also fixes #1722.
Closes #1544.
Closes #1613.
@vladikoff - great catch - it could be! I fixed it [in this commit](https://github.com/mozilla/fxa-content-server/commit/a91e27b5ad74798fbf99c5974966da7c0b0469c0#diff-b80f22cfd726dfdc2bb7ed3e82dc7264R296) after I added more tests for the web channel in PR #1824.