[#488] reputation: Change Writer interface

Includes:
- Delete first `ctx` argument in `Write` method.
- Move intermediate Initial trust struct and method
to `calculator` file.
- Change Alpha to 0.1.

Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>

pkg/services/reputation/common/deps.go

@@ -29,7 +29,7 @@ type Writer interface {
 	// Close operation.
 	//
 	// Write must not be called after Close.
-	Write(Context, reputation.Trust) error
+	Write(reputation.Trust) error
 
 	// Close exits with method-providing Writer.
 	//