Nicer handling of timeline archival for Cloud storage

- When append() is not supported, rollover to new file always (instead of failing)
 - Provide way to configure archive log folder (avoids small files inside .hoodie)
 - Datasets written via Spark datasource archive to .hoodie/archived
 - HoodieClientExample will now retain only 2,3 commits to exercise archival path during dev cycles
 - Few tweaks to code structure around CommitArchiveLog

hoodie-hadoop-mr/src/test/java/com/uber/hoodie/hadoop/realtime/HoodieRealtimeRecordReaderTest.java

@@ -72,6 +72,7 @@ public class HoodieRealtimeRecordReaderTest {
     jobConf = new JobConf();
     fs = FSUtils
         .getFs(basePath.getRoot().getAbsolutePath(), HoodieTestUtils.getDefaultHadoopConf());
+    HoodieTestUtils.fs = fs;
   }
 
   @Rule