json-ld for sesame. Taken from Pull Request #61
fixes following on remarks by @betehess on PR #141
allow user definable RDFOps[Sesame] for Readers
minor fix
[sesame] Fixes and enhancement for #141.

* removes the type hierarchy on the syntaxes
* better use of typeclass instances
* removes unwanted mixin on the top-level package object
Merge pull request #141 from read-write-web/topic/json-ld

json-ld for sesame.