Impl. of the metadata getters.

In Metadata, implemented the method that unmarshall the data from
a metadata parcel an return java entities.

Add 2 new types of metadata (Boolean and Date) and fixed an issue
in TimedText: the w3c standard specify a duration as well as the
time to be played => added a duration field.

In MetadataParserTest.java:
Moved the util private methods at the bottom of the file.
Added new tests for the getters (GETTERS section)