Split POM license declaration in two.

The Maven POM allows one to specify multiple licenses. This is useful for dual (or triple) licensed projects such as Jersey. However, Jersey currently:
- ...declares its licenses in a single `<license>` element, using the plus sign.
- ...doesn't declare the version of the licenses used.

Both these things are inconvenient for users of the [`license-maven-plugin`](http://mojo.codehaus.org/license-maven-plugin/), as it doesn't allow one to "[_merge_](http://mojo.codehaus.org/license-maven-plugin/add-third-party-mojo.html#licenseMerges)" the licenses with other uses of the _CDDL 1.1_ and/or _GPLv2 with classpath exception_.

The change proposed by this pull request distributes the license declaration over two `<license>` elements. (NB: If you accept this patch, note that the HK2 POMs should similarly be updated.)