Add license

[vemonet]

It is usually highly recommended to provide a license with publicly published code

Should the GraphDB license agreement be added for this repo?

e.g. http://graphdb.ontotext.com/LICENSE-GraphDB-Free.txt or the Apache 2 https://github.com/Ontotext-AD/graphdb-workbench/blob/master/licenses/LICENSE

[vemonet]

#14 Pull request to add Apache 2 license from the graphdb-workbench repository

https://github.com/Ontotext-AD/graphdb-workbench/blob/master/licenses/LICENSE