HL7v2 path information should be used when generating NAKs after failed message validation

[unixoid]

The IPF's HL7v2 DSL is now able to track path information. This data should be used to fill the "location" field of the Hl7v2Exception when a such exception is thrown (e. g. after failed message validation).

[unixoid]

This issue is related to #31.

[unixoid]

Should the path tracking have been implemented in HAPI instead of IPF?..