Upgrade to DKPro Core 1.7.0

[logological]

We should probably upgrade to DKPro Core 1.7.0. This would allow for interoperability with other DKPro products which also depend on Core 1.7.0, such as DKPro TC. However, we do depend on other DKPro products which may depend on earlier versions of Core (DKPRo LSR, DKPro Similarity, UBY, and possibly others).

[logological]

Seems to have been fixed in the development version. DKPro WSD and UBY depend on DKPro Core 1.7.0; DKPro LSR doesn't seem to depend on DKPro Core at all. The DKPro Similarity version we are using (2.1.0) might need to be upgraded.