[CONFIGURATION-639] Mark Spring-dependencies as optional.
[CONFIGURATION-639] Mark Spring-dependencies as optional.

The configuration of the OSGi plugin was changed to declare
Spring-dependencies as optional. Thanks to Rico Neubauer for the
patch.

git-svn-id: 0d31da9e303333003508381311333cf78a25d41b@1765164 13f79535-47bb-0310-9956-ffa450edef68

apache/commons-configuration,apache/commons-configuration,apache/commons-configuration