restore SF nuget packages

Merge pull request c3-ls#38 from c3-ls/retry

New HTTP-404 retry behavior; HTTP-5xx retries off by default

fixes c3-ls#32 - ASP.NET Core RTM

c3-ls#24 IConfiguration based settings to add multiple gateways from …

…a file, database, ...

c3-ls#9 Upgrade to rc2-final

downgraded version for bugfix release

fixes c3-ls#2 (Provide a way to disable retries on StatusCode errors)

another try to fix the artifacts-path