[#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/local/storage/calls.go

@@ -47,7 +47,7 @@ type EpochTrustValueStorage struct {
 
 func newTrustValueStorage() *EpochTrustValueStorage {
 	return &EpochTrustValueStorage{
-		mItems:     make(map[string]*trustValue, 1),
+		mItems: make(map[string]*trustValue, 1),
 	}
 }