Update SDK to File API v2

[dimitrystd]

Smartling File API v2 will be released soon. SDK should be ready for this release.

DoD:

• Cover in SDK mandatory methods:
  • [x] Upload file
  • [x] Download file
  • [x] File Status (for locale)
  • [x] File Status (for all locales)
  • [x] Last modified (for locale)
  • [x] Last modified (for all locales)
  • [x] Authorize Locales
  • [x] Un-authorize Locales
  • [x] Delete File
  • [x] List Files
• Each subtask above includes:
  • Unit tests
  • Integration test
• Implemented new authentication flow via API gateway
  • [x] OAuth flow
  • [x] Caching refresh_token and access_token
  • [x] Request new token in case of expiration or 401
• [x] Sample app is updated
• [x] New version is published in nuget

Note: Please keep in mind that scope of this task only about FAPI, but this sdk will also contain implementations for Projects and Jobs APIs.

[dimitrystd]

We had some discussions for java, probably it will be useful https://github.com/Smartling/api-sdk-java/issues/24. Also pls look and java sdk implementation

[dotnetrocks]

I suppose the "List" and "Delete" methods are also mandatory, right?

[dimitrystd]

Yes, let's implement them. We don't know who uses sdk except connectors, but it will be convenient to have them

[dotnetrocks]

Done & uploaded to Nuget: https://www.nuget.org/packages/Smartling.Api/ There might be some tweaks during integration with Sitecore Connector.

I did not implement Builder pattern / Async (mentioned in Java thread). Please reopen if it is needed.

Sample app updated & it can now use env. variables instead of entering token/secret each time.