fix(directline.interface): fix tslint errors

Author: harshithkashyap

src/directline.interface.ts

@@ -20,7 +20,7 @@ export interface Media {
     thumbnailUrl?: string
 }
 
-export interface UnknownMedia{
+export interface UnknownMedia {
     contentType: string,
     contentUrl: string,
     name?: string,
@@ -235,9 +235,9 @@ export interface DirectLineOptions {
 
 export interface IBotConnection {
     connectionStatus$: BehaviorSubject<ConnectionStatus>,
+    referenceGrammarId?: string,
+    getSessionId?: () => Observable<string>
     activity$: Observable<Activity>,
     end(): void,
-    referenceGrammarId?: string,
     postActivity(activity: Activity): Observable<string>,
-    getSessionId? : () => Observable<string>
-}
+}