Adding hoodie-spark to support Spark Datasource for Hoodie

- Write with COW/MOR paths work fully
 - Read with RO view works on both storages*
 - Incremental view supported on COW
 - Refactored out HoodieReadClient methods, to just contain key based access
 - HoodieDataSourceHelpers class can be now used to construct inputs to datasource
 - Tests in hoodie-client using new helpers and mechanisms
 - Basic tests around save modes & insert/upserts (more to follow)
 - Bumped up scala to 2.11, since 2.10 is deprecated & complains with scalatest
 - Updated documentation to describe usage
 - New sample app written using the DataSource API

hoodie-common/src/main/java/com/uber/hoodie/common/util/ParquetUtils.java

@@ -30,6 +30,7 @@ import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.Path;
 import org.apache.parquet.avro.AvroParquetReader;
 import org.apache.parquet.avro.AvroReadSupport;
+import org.apache.parquet.avro.AvroSchemaConverter;
 import org.apache.parquet.hadoop.ParquetFileReader;
 import org.apache.parquet.hadoop.ParquetReader;
 import org.apache.parquet.hadoop.metadata.ParquetMetadata;
@@ -126,7 +127,7 @@ public class ParquetUtils {
         List<String> footerVals = new ArrayList<>();
         ParquetMetadata footer = readMetadata(parquetFilePath);
         Map<String, String> metadata = footer.getFileMetaData().getKeyValueMetaData();
-        for (String footerName: footerNames) {
+        for (String footerName : footerNames) {
             if (metadata.containsKey(footerName)) {
                 footerVals.add(metadata.get(footerName));
             } else {
@@ -137,6 +138,10 @@ public class ParquetUtils {
         return footerVals;
     }
 
+    public static Schema readAvroSchema(Path parquetFilePath) {
+        return new AvroSchemaConverter().convert(readSchema(parquetFilePath));
+    }
+
     /**
      * Read out the bloom filter from the parquet file meta data.
      */