CHANGELOG for version 0.13

Bug Fixes:
- Register image w. upload but no metafile [#4864]
- Minor typos and updates in command help messages
- All URL-related params are now URL-encoded [#4986]
- In file list, show all directories as directories [#4987]
- Do not let file-* cmds to create containers [#4992]

Features:
- Name and Type filters in endpoint list
- In image register, meta gets same sharing as image [#4960]
- Allow image register to auto-resolve remote path from local file [#4991]
- Merge ClientError and AstakosClientException --> AstakosClientError [#5002]
- Restore kamaki file publish/unpublish
- Accept username or UUID in kamaki file --account/--to-account [#4810]