Include example BIDS data

[thomshaw92]

I was wondering if you had an example of the minimum BIDS inputs I would need to get going with the MRtrix3 connectome BIDSApp? Is there perhaps an example dataset?
Thanks for all your help!

[Lestropie]

@thomshaw92: While not comprehensive, the 0.5.0 update in #62 performs Continuous Integration testing of all three analysis levels, where for each it downloads test data from this OSF project. Longer-term I'd like to have sample data where it tests all compatible DWI acquisition strategies, but perhaps for now this shows some examples of what the data look like.