Swagger: Revert BinaryResponse type to string

Go-swagger does not appear to support `"format": "binary"`, and `"$ref": "#/definitions/File"` doesn't seem to be supported. Resolves #188

server/apiv1/swagger.go

@@ -1,7 +1,5 @@
 package apiv1
 
-import "os"
-
 // These structs are for the purpose of defining swagger HTTP responses
 
 // Application information
@@ -148,10 +146,7 @@ type linkCheckParams struct {
 
 // Binary data response inherits the attachment's content type
 // swagger:response BinaryResponse
-type binaryResponse struct {
-	// in: body
-	File os.File
-}
+type binaryResponse string
 
 // Plain text response
 // swagger:response TextResponse
@@ -161,7 +156,7 @@ type textResponse string
 // swagger:response HTMLResponse
 type htmlResponse string
 
-// Error response
+// HTTP error response will return with a >= 400 response code
 // swagger:response ErrorResponse
 type errorResponse string
 

server/ui/api/v1/swagger.json

@@ -809,11 +809,6 @@
       "x-go-name": "deleteMessagesRequestBody",
       "x-go-package": "github.com/axllent/mailpit/server/apiv1"
     },
-    "File": {
-      "type": "object",
-      "title": "File represents an open file descriptor.",
-      "x-go-package": "os"
-    },
     "HTMLCheckResponse": {
       "description": "Response represents the HTML check response struct",
       "type": "object",
@@ -1387,11 +1382,11 @@
     "BinaryResponse": {
       "description": "Binary data response inherits the attachment's content type",
       "schema": {
-        "$ref": "#/definitions/File"
+        "type": "string"
       }
     },
     "ErrorResponse": {
-      "description": "Error response",
+      "description": "HTTP error response will return with a \u003e= 400 response code",
       "schema": {
         "type": "string"
       }