[Test] Added test to confirm CDATA is parsed in oai_dc metadata entries
[Test] Added simplet test to confirm normal behaviour of set parsing
[Refactor] Added a parse() method to ListSetsParser to harmonise methods with other parsers. ListSetsHandler now uses this method
[Test] Added first test with CDATA - test is passing
[Refactor] Simplified code in test.
[Test] Added example with 2 CDATA elements in RecordParserTest
[Fix] Added additional while within ListSetParser so it doesn't stop reading data after the first CDATA element is found