Unsupported HTTP methods should return 405 and the methods allowed

[vgkholla]

Currently RestServiceErrorCode.UnsupportedHttpMethod maps to a 400 status code. Instead it should map to 405 and should return the methods allowed (POST, GET, DELETE and HEAD).

[vgkholla]

This does present a problem because a BlobStorageService might not support all of POST, GET, DELETE and HEAD (AdminBlobStorageService does not support POST) but they can handle the 405 independently. The user experience might be inconsistent in this case but this stop gap solution can work until we find a more elegant solution.

[ghost]

Well the idea should be splitting the BlobStorageService interface, for the sake of Interface segregation principle. What do you think having a different interface for each use case. It would be

class AdminBlobStorageService implements BlobStorageService, HttpGetAwareRequest, HttpDeleteAwareRequest, HttpHeadAwareRequest  { ... }

Or is it too bloated?