MyriaRelation should support indexing

[dhutchis]

In the MyriaRelation class, there should be support for indexing. Indexing into a MyriaRelation is part of the example iPython notebook and seems like a very useful feature. Instead I see the following:

TypeError: 'MyriaRelation' object does not support indexing

for the example on the demo server

dataset = connection.datasets()[0]
MyriaRelation(dataset['relationKey'])[-1]

Removing the [-1] runs fine.

[shrjain]

It would be good to have indexing, but you can do the following for now maybe
MyriaRelation(dataset['relationKey']).to_dict()

[dhutchis]

Yep, that and the rest of the examples work fine. So this is a small note. The indexing should be added or the example notebook should be changed.