Azure Storage File Go SDK v0.3.0

• Redact sig query parameter in copy source header.
• Optimize retry logics that better handles net.Error and fix the context leak.
• Update content md5 definitions.
• Use latest spec and autorest generated code which optimized error handling and metadata validation.
• Other optimizations done through aligning to blob SDK.
• Optimize examples using azfile package as customer do.
• Add CI support.
• Add issue template.
• Remove swagger spec, which is language agnostic.