DATAJDBC-411 - Set project.root in module poms to correctly generate Javadoc.

By setting project.root, Javadoc is aggregated in the parent pom target so it can be collected during the distribution build.

Original pull request: #168.

spring-data-jdbc/pom.xml

@@ -19,6 +19,7 @@
 
 	<properties>
 		<java-module-name>spring.data.jdbc</java-module-name>
+		<project.root>${basedir}/..</project.root>
 	</properties>
 
 	<inceptionYear>2017</inceptionYear>

spring-data-relational/pom.xml

@@ -18,6 +18,7 @@
 
 	<properties>
 		<java-module-name>spring.data.relational</java-module-name>
+		<project.root>${basedir}/..</project.root>
 	</properties>
 
 	<dependencies>