Implemented Time Validity Metric and assorted small fixes.
- Developed first version Time Validity Interval metric and the corresponding Unit Test.
- Added Volatility dimension and Time Validity Interval metric to the DQM ontology.
- Slight improvements in logging statements at CurrencyDocumentsStatements.java and ExclusionOutdatedData.java.
- Moved Currency tests to appropriate package: ...dynamicity.currency.
- Made nested class ComparableSubject static, part of the Extensional Conciseness metric.
- Improved/extended the sample data used to test Currency metrics (SampleInput_Currency.ttl).