Moved some classes to more appropriate packages

...a/info/textgrid/services/aggregator/AbstractExporter.java

src/main/java/info/textgrid/services/aggregator/REST.java

src/main/java/info/textgrid/services/aggregator/Version.java

...nfo/textgrid/services/aggregator/epub/EPUBSerializer.java

...va/info/textgrid/services/aggregator/html/HTMLWriter.java

src/main/java/info/textgrid/services/aggregator/pdf/PDF.java

...id/services/aggregator/teicorpus/CorpusBasedExporter.java

...id/services/aggregator/teicorpus/TEICorpusSerializer.java

...extgrid/services/aggregator/teicorpus/TEIHeaderStack.java

...grid/services/aggregator/tree/AggregationTreeFactory.java

...tgrid/services/aggregator/tree/AggregationTreeWalker.java

.../textgrid/services/aggregator/util/StylesheetManager.java

...extgrid/services/aggregator/util/TextGridRepProvider.java

.../textgrid/services/aggregator/util/XSLTErrorListener.java

src/main/webapp/WEB-INF/beans.xml

...o/textgrid/services/aggregator/StylesheetManagerTest.java

...va/info/textgrid/services/aggregator/TextGridRepTest.java

...textgrid/services/aggregator/teicorpus/TEICorpusTest.java

...rid/services/aggregator/teicorpus/TEIHeaderStackTest.java