Update changelog/ for new version of calens

We've reworked calens[1] a bit, the changelog/releases file is not
needed any more. Insteady, the release date is stored in the dir name
which contains the changelog entries.

[1] https://github.com/restic/calens

changelog/0.7.0_2017-07-01/issue-1013

@@ -0,0 +1,9 @@
+Bugfix: Switch back to using the high-level minio-go API for s3
+
+For the s3 backend we're back to using the high-level API the s3 client library
+for uploading data, a few users reported dropped connections (which the library
+will automatically retry now).
+
+https://github.com/restic/restic/issues/1013
+https://github.com/restic/restic/issues/1023
+https://github.com/restic/restic/pull/1025

changelog/0.7.0_2017-07-01/issue-1021

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+Enhancement: Detect invalid backend name and print error
+
+restic now tries to detect when an invalid/unknown backend is used and
+returns an error message.
+
+https://github.com/restic/restic/issues/1021
+https://github.com/restic/restic/pull/1070

changelog/0.7.0_2017-07-01/issue-1029

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+Enhancement: Remove invalid pack files when `prune` is run
+
+The `prune` command has been improved and will now remove invalid pack files,
+for example files that have not been uploaded completely because a backup was
+interrupted.
+
+https://github.com/restic/restic/issues/1029
+https://github.com/restic/restic/pull/1036

changelog/0.7.0_2017-07-01/issue-512

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+Enhancement: Add Backblaze B2 backend
+
+https://github.com/restic/restic/issues/512
+https://github.com/restic/restic/pull/978

changelog/0.7.0_2017-07-01/issue-636

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+Enhancement: Add dirs `tags` and `hosts` to fuse mount
+
+The fuse mount now has two more directories: `tags` contains a subdir for
+each tag, which in turn contains only the snapshots that have this tag. The
+subdir `hosts` contains a subdir for each host that has a snapshot, and the
+subdir contains the snapshots for that host.
+
+https://github.com/restic/restic/issues/636
+https://github.com/restic/restic/pull/1050

changelog/0.7.0_2017-07-01/issue-965

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+Bugfix: Switch to `default` repo layout for the s3 backend
+
+The default layout for the s3 backend is now `default` (instead of `s3legacy`).
+Also, there's a new `migrate` command to convert an existing repo, it can be
+run like this: `restic migrate s3_layout`
+
+https://github.com/restic/restic/issues/965
+https://github.com/restic/restic/pull/1004

changelog/0.7.0_2017-07-01/issue-989

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+Enhancement: Improve performance of the `find` command
+
+Improved performance for the `find` command: Restic recognizes paths it has
+already checked for the files in question, so the number of backend requests
+is reduced a lot.
+
+https://github.com/restic/restic/issues/989
+https://github.com/restic/restic/pull/993

changelog/0.7.0_2017-07-01/pull-975

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+Enhancement: Add new backend for OpenStack Swift
+
+https://github.com/restic/restic/pull/975
+https://github.com/restic/restic/pull/648

changelog/0.7.0_2017-07-01/pull-998

@@ -0,0 +1,5 @@
+Enhancement: Improve performance of the fuse mount
+
+Listing directories which contain large files now is significantly faster.
+
+https://github.com/restic/restic/pull/998