Added related work; compatibleWith; copyrightHolder; copyrightYear

@JeniT could you take a look over this pull request. I've made several revisions to the vocabulary, publisher guide and examples:

* Removed copyrightNotice in favour of copyrightHolder and copyrightYear. This decomposes things into simpler properties as suggested in #9 (although doesn't include every change proposed there)
* Added compatibleWith relationship between licenses, with wording taken from [here](http://opensource.com/law/11/9/mpl-20-copyleft-and-license-compatibility)
* Added some additional links to the Related Work section

I've revised examples accordingly. The only potential downside with the changes to using more fine-grained copyright notices is that it provides less options for publishers to specify a specific form of notice, which might be required for some jurisdictions (I'm not 100% clear). It also means that more complex statements like that required by the OS need to be relegated to a separate copyright statement -- although that could be a good thing as it encouraged linking rather than placing more expectations on re-users.