Upgrade to spring 3.0.6.RELEASE to stop spring version mix in drools-camel-server

drools-camel-server [master $] $ mvn dependency:tree
...
[INFO] --- maven-dependency-plugin:2.2:tree (default-cli) @ drools-camel-server ---
...
[INFO] +- org.drools:drools-spring:jar:5.4.0-SNAPSHOT:compile
[INFO] |  +- org.springframework:spring-beans:jar:2.5.6:compile
[INFO] |  \- org.springframework:spring-context:jar:2.5.6:compile
...
[INFO] +- org.apache.camel:camel-spring:jar:2.9.0:compile
[INFO] |  \- org.springframework:spring-tx:jar:3.0.6.RELEASE:compile
....
[INFO] +- org.springframework:spring-core:jar:2.5.6:compile
[INFO] +- org.springframework:spring-aop:jar:2.5.6:compile
[INFO] +- org.springframework:spring-web:jar:2.5.6:compile
[INFO] +- org.springframework:spring-test:jar:2.5.6:test
[INFO] +- org.apache.cxf:cxf-bundle-jaxrs:jar:2.4.4:compile
...
[INFO] |  +- org.springframework:spring-asm:jar:3.0.6.RELEASE:compile
[INFO] |  +- org.springframework:spring-expression:jar:3.0.6.RELEASE:compile
...