Improve reading from and writing to Metadata pages

This change introduces a new interface IComponentMetadata.
Each LSM component is associated with a metadata object
which can be used to read and write arbitrary data to
the metadata pages of components. When flushing a
component, data in its metadata component is automatically
flushed to the disk component. For merge operations,
the IO Callback is responsible for merging the components'
metadata pages.

Change-Id: Id95ef33c0a0bc1abb3fc3ecdea5611ee4acd6dfa
Reviewed-on: https://asterix-gerrit.ics.uci.edu/1476
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Ian Maxon <imaxon@apache.org>
Integration-Tests: Ian Maxon <imaxon@apache.org>
Integration-Tests: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
diff --git a/hyracks-fullstack/algebricks/algebricks-rewriter/pom.xml b/hyracks-fullstack/algebricks/algebricks-rewriter/pom.xml
index 2488c3f..386b824 100644
--- a/hyracks-fullstack/algebricks/algebricks-rewriter/pom.xml
+++ b/hyracks-fullstack/algebricks/algebricks-rewriter/pom.xml
@@ -16,18 +16,15 @@
  ! specific language governing permissions and limitations
  ! under the License.
  !-->
-
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
   <modelVersion>4.0.0</modelVersion>
   <artifactId>algebricks-rewriter</artifactId>
   <name>algebricks-rewriter</name>
-
   <parent>
     <groupId>org.apache.hyracks</groupId>
     <artifactId>algebricks</artifactId>
     <version>0.3.1-SNAPSHOT</version>
   </parent>
-
   <licenses>
     <license>
       <name>Apache License, Version 2.0</name>
@@ -36,11 +33,9 @@
       <comments>A business-friendly OSS license</comments>
     </license>
   </licenses>
-
   <properties>
     <root.dir>${basedir}/../..</root.dir>
   </properties>
-
   <dependencies>
     <dependency>
       <groupId>org.apache.hyracks</groupId>
@@ -62,4 +57,4 @@
       <artifactId>commons-lang3</artifactId>
     </dependency>
   </dependencies>
-</project>
+</project>
\ No newline at end of file