Add Apache License

Infinispan as one of the main use cases of JBoss Marshalling is licensed under Apache License, but has a dependency on JBoss Marshalling, which still has LGPL license. This makes it impossible to use Infinispan in Apache Marmotta (or other Apache projects), because the LGPL is considered to be incompatible with the Apache License:

http://www.apache.org/legal/3party.html#criteriaandcategories

Please consider relicensing to Apache License. It would make the library much more usable.

Related to ISPN-3848