Adding range based pruning to bloom index

- keys compared lexicographically using String::compareTo
 - Range metadata additionally written into parquet file footers
 - Trim fat & few optimizations to speed up indexing
 - Add param to control whether input shall be cached, to speed up lookup
 - Add param to turn on/off range pruning
 - Auto compute of parallelism now simply factors in amount of comparisons done
 - More accurate parallelism computation when range pruning is on
 - tests added & hardened, docs updated

hoodie-common/src/main/java/com/uber/hoodie/exception/HoodieIndexException.java

@@ -16,8 +16,6 @@
 
 package com.uber.hoodie.exception;
 
-import java.io.IOException;
-
 /**
  * <p>
  * Exception thrown for HoodieIndex related errors.

hoodie-common/src/main/java/com/uber/hoodie/exception/MetadataNotFoundException.java

@@ -0,0 +1,32 @@
+/*
+ *  Copyright (c) 2017 Uber Technologies, Inc. (hoodie-dev-group@uber.com)
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *           http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ *
+ */
+
+package com.uber.hoodie.exception;
+
+/**
+ * Thrown when expected metadata is not found
+ */
+public class MetadataNotFoundException extends HoodieException {
+    public MetadataNotFoundException(String msg) {
+        super(msg);
+    }
+
+    public MetadataNotFoundException(String msg, Throwable e) {
+        super(msg, e);
+    }
+}