Adds requirements for Fedora's alpha-6 implementation of LDP.

Uses PUT/POST appropriately for creating a new record with an ID.
A resource is defined by LDP#DirectContainer
Updates etag and last-modified in cached response when updating - stops
412 errors on repeated saves.
I see both #Resource and #DirectContainer headers:

```
< HTTP/1.1 200 OK
< ETag: "cd93612c87d133785390ced92850a8c13b3fc397"
< Last-Modified: Wed, 04 Jun 2014 19:02:59 GMT
< Preference-Applied: return=representation; include="http://www.w3.org/ns/ldp#PreferMembership http://www.w3.org/ns/ldp#PreferContainment http://fedora.info/definitions/v4/repository#InboundReferences"
< Vary: Prefer
< Accept-Patch: application/sparql-update
< Allow: MOVE,COPY,DELETE,POST,HEAD,GET,PUT,PATCH,OPTIONS
< Accept-Post: text/turtle,text/rdf+n3,application/n3,text/n3,application/rdf+xml,application/n-triples,multipart/form-data,application/sparql-update
< Link: <http://www.w3.org/ns/ldp#Resource>;rel="type"
< Link: <http://www.w3.org/ns/ldp#DirectContainer>;rel="type"
< Content-Type: text/turtle
< Transfer-Encoding: chunked
* Server Jetty(9.1.5.v20140505) is not blacklisted
< Server: Jetty(9.1.5.v20140505)
```