Refactor pom.xml files in controller repo

We should look into refactoring the pom.xml files in the controller repo to take advantage of Maven pom inheritance. For example the <scm> section is duplicated in multiple pom.xml files:

<scm>
<connection>scm:git:ssh://git.opendaylight.org:29418/controller.git</connection>
<developerConnection>scm:git:ssh://git.opendaylight.org:29418/controller.git</developerConnection>
<url>https://wiki.opendaylight.org/view/OpenDaylight_Controller:Main</url>
<tag>HEAD</tag>
</scm>

A quick count shows that the <scm> section exists in 162 pom.xml files. If the scm URL ever changes this means we'd have to update that in 162 locations which isn't very clean and maintainable.

% find . -name pom.xml | xargs grep '<scm>' | wc -l
162

I'd like to use this bug as a master bug and tackle this issue with many small and easy to review patches to simplify the pom.xml layout for the repo.