bugfix replace space with tab in sample/rel.csv

The relations file in `sample/rels.csv` is not correct formatted. The columns `type` and `since` are separated by a space instead of a tab. 
This result in:

    {"endNodeId":4,"relationshipType":"FATHER_OF 2008-05-03","id":2,"propertyMap":{"since":"3"}}

instead of:

    {"endNodeId":4,"relationshipType":"FATHER_OF","id":2,"propertyMap":{"counter":3,"since":"2008-05-03"}}


Accepting all white spaces as separators or better using commas to separate the columns would make it a lot
easier to spot this kind of errors.

Best,
Immanuel