Release v0.51.1

Merge pull request mozilla#2595 from mozilla/release-v0.51.0-signed

Release v0.51.0

Merge pull request mozilla#2593 from mozilla/0.50.2

Release v0.50.2

Merge pull request mozilla#2592 from mozilla/0.50.1

Don't use a bool argument over the FFI in fxa_migrate_from_session_token

Merge pull request mozilla#2586 from mozilla/0.50.x; r=grigoryk

Release v0.50.0

Release v0.49.0

Merge pull request mozilla#2523 from mozilla/rel48212

Release v0.48.3

Merge pull request mozilla#2467 from mozilla/rel-x12

Cut release 0.48.2

Merge pull request mozilla#2452 from mozilla/rel-481-rel

Cut release 0.48.1

Merge pull request mozilla#2429 from mozilla/rel-z

Cut release 0.48.0