Multi FS Support

- Reviving PR 191, to make FileSystem creation off actual path
 - Streamline all filesystem access to HoodieTableMetaClient
 - Hadoop Conf from Spark Context serialized & passed to executor code too
 - Pick up env vars prefixed with HOODIE_ENV_ into Configuration object
 - Cleanup usage of FSUtils.getFS, piggybacking off HoodieTableMetaClient.getFS
 - Adding s3a to supported schemes & support escaping "." in env vars
 - Tests use HoodieTestUtils.getDefaultHadoopConf

hoodie-spark/src/test/scala/DataSourceTest.scala

@@ -57,7 +57,7 @@ class DataSourceTest extends AssertionsForJUnit {
     val folder = new TemporaryFolder
     folder.create
     basePath = folder.getRoot.getAbsolutePath
-    fs = FSUtils.getFs
+    fs = FSUtils.getFs(basePath, spark.sparkContext.hadoopConfiguration)
   }
 
   @Test def testCopyOnWriteStorage() {