cf v6.0.1

Here's a list of features and fixes in v6.0.1 maintenance release:

• Added purge-service-offering and migrate-service-instances commands
• Added -a flag to org-users command that makes the command display all users, rather than only privileged users (#46)
• Fixed a bug when manifest.yml was zero bytes
• Improved error messages for commands that reference users (#79)
• Fixed crash when a manifest didn't contain environment variables but there were environment variables set for the app previously
• Improved error messages for commands that require an API endpoint to be set
• Added timeout to all asynchronous requests
• Fixed 'bad file descriptor' crash when API token expired before file upload
• Added timestamps and version information to request logs when CF_TRACE is enabled
• Added fallback to default log server endpoint for compatibility with older CF deployments
• Improved error messages for services and target commands
• Added support for URLs as arguments to create-buildpack command
• Added a homebrew recipe for cf -- usage: brew install cloudfoundry-cli