Migrate to S4 Classes

Change-Id: I27e9452e9d59f6b414898390074908ec0e91e2a9
diff --git a/DESCRIPTION b/DESCRIPTION
index a554477..e85a540 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -12,4 +12,10 @@
 Imports:
     curl,
     jsonlite,
-    utils
+    utils,
+    httr,
+    methods
+Collate: 
+    'KorAPConnection.R'
+    'KorAPCorpusStats.R'
+    'KorAPQuery.R'