Automatic testing of NIDM export in SPM

Please note that this pull request is based on #119 (PR #119 should be reviewed first).

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This pull request allows to automatically test that the NIDM export stored in `nidm/nidm-results/test/spmexport/example001` is consistent with `nidm-results.owl` and is identical to the gold standard specified in `nidm/nidm-results/spm/example001`. 

Automatic testing is done using Travis CI as discussed in #106.