How to contribute? Support for SERVICE clause

[Jerven Tjalling Bolleman]

Dear RDFlib developers,

Thank you very much for making a great set of libraries that we can use.

I took the work started by @marqh to continue making sparql 1.1 service
queries possible [1].

For me it is unclear what I need to do so that this can be merged into
master.
I added tests and travis passes for all supported python versions.
So I was hopeing for a few pointers/review to have my start continue.

Regards,
Jerven

[1] https://github.com/RDFLib/rdflib/pull/943

--
Jerven Tjalling Bolleman
SIB | Swiss Institute of Bioinformatics
CMU - 1, rue Michel Servet - 1211 Geneva 4
t: +41 22 379 58 85 - f: +41 22 379 58 58
Jerven....@sib.swiss - http://www.sib.swiss