Register trampoline.biz.port and trampoline.view.port as system properties for both Biz and View

See http://maven.apache.org/pom.html#Plugins and
http://blog.sonatype.com/people/2011/01/maven-how-to-merging-plugin-configuration-in-complex-projects/
about Maven configuration inheritance and combine.children attribute.
Register PropertySourcesPlaceholderConfigurer to be able to resolve
system properties (and other properties) inside Spring context

See http://static.springsource.org/spring/docs/3.2.x/spring-framework-reference/html/beans.html#beans-factory-placeholderconfigurer
and http://blog.springsource.com/2011/02/15/spring-3-1-m1-unified-property-management/
Use system property instead of hardcoded value for biz http port