fix missing xml elements in pom.xml

[sreev]

HW14169:streamline svaddi$ mvn clean
[INFO] Scanning for projects...
[WARNING]
[WARNING] Some problems were encountered while building the effective model for com.hortonworks.streamline:streamline-findbugs:jar:0.3
[WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-site-plugin is missing. @ line 14, column 21
[WARNING]
[WARNING] Some problems were encountered while building the effective model for com.hortonworks.streamline:custom-udf-microtest:jar:0.6.0-SNAPSHOT
[WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-compiler-plugin is missing. @ com.hortonworks.streamline:custom-udf-microtest:[unknown-version], /Users/svaddi/SreeVaddi/sources/github/sreev/streamline/streams/test-support/custom-udf-microtest/pom.xml, line 30, column 21
[WARNING]
[WARNING] Some problems were encountered while building the effective model for com.hortonworks.streamline:hortonworks-streamline-docker:pom:0.6.0-SNAPSHOT
[WARNING] The expression ${parent.version} is deprecated. Please use ${project.parent.version} instead.
[WARNING] The expression ${parent.version} is deprecated. Please use ${project.parent.version} instead.
[WARNING] The expression ${parent.version} is deprecated. Please use ${project.parent.version} instead.
[WARNING]
[WARNING] It is highly recommended to fix these problems because they threaten the stability of your build.
[WARNING]
[WARNING] For this reason, future Maven versions might no longer support building such malformed projects.
[WARNING]