Introduction of new Gelly developper

[Yi ZHOU]

Hello, everyone,

I am ZHOU Yi, a student working in graph algorithm, especially graph 
combinatorial algorithms. I am glad to join the Flink devlopping group.

I am working on Gelly graph library, hopping to devote improvements and 
new features to Gelly graph library (algorithms library, graph partition 
improvements etc. issue26 
<https://github.com/project-flink/flink-graph/issues/20>). Now,  I plan 
to start  with affinity propagation example Flink-1707 
<https://issues.apache.org/jira/browse/FLINK-1707>.

My apache account on appache is joey00! (a little bizzare ;-) ) , my 
github account is joey001. I have joined several lab group projects 
(AUTOSAR, TTCN-3), but don't much open source experience, especially 
large project like Flink.  Your suggestions and comments will be welcomed.

Best Regards.
ZHOU Yi