Inconsistent HeaderFields fields

[fabiante]

During implementation of #14 I noticed that the search endpoints returns more header fields. In terms of the Golang type:

easclient/record.go

Line 9 in 4ef82e3

type HeaderFields struct {

These fields were present in the search endpoint response.

Index: record.go
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/record.go b/record.go
--- a/record.go	(revision 4463323439056851ca8f236f5158ffe441e5685e)
+++ b/record.go	(revision da8442942381fccc168abab10ace1934e4d49ae5)
@@ -13,6 +13,8 @@
 	Id                     uuid.UUID `json:"_id"`
 	Version                string    `json:"_version"`
 	ArchiverLogin          string    `json:"_archiverLogin"`
+	Archiver               string    `json:"_archiver"`
+	InitialArchiver        string    `json:"_initialArchiver"`
 	InitialArchiverLogin   string    `json:"_initialArchiverLogin"`
 	InitialArchiveDateTime time.Time `json:"_initialArchiveDateTime"`
 }

This may or may not cause issues. We should have a look at this some time.