esutils: cleanup and rewrite without xslt transformation for jaxb to json mapping
the textgrid-metadata xml to json for elasticsearch conversion was done quick and dirty and has lots of string to object and back transformation.
we should test the the following
- map from incoming jaxb to outgoing jackson object without xslt transformation
- instead of xslt use some simple stax parser for text extraction
this should lead to cleaner code and better performance