Release v0.7.0

Merge pull request notaryproject#1338 from cyli/changelog-version-0.6.1

Bump notary version to 0.6.1 and add changelog.

Merge branch 'release/0.6.0' into releases

Signed-off-by: Ying Li <[email protected]>

Merge pull request notaryproject#1214 from endophage/changefeed

changefeed for rethinkdb

Merge pull request notaryproject#1076 from cyli/changelog-update

Update changelog and version for 0.4.4

Merge pull request notaryproject#1067 from riyazdf/delegation-key-imp…

…ort-export

Fix delegation key import/export GUN inference logic

Release v0.5.0

Finished hotfix 0.4.2.

Finished hotfix 0.4.1.

Finished release 0.4.0.