FileDataStore: only open a stream when really necessary

Currently, PropertyImpl.getValue() opens a FileInputStream if the FileDataStore is used.
If the application doesn't use the value, this stream is never closed.

PropertyImpl.getValue():
return internalGetValue().toJCRValue(session);
InternalValue.toJCRValue(..):
case PropertyType.BINARY:
return new BinaryValue(((BLOBFileValue) val).getStream());
BLOBInDataStore.getStream():
return getDataRecord().getStream();
FileDataRecord.getStream():
return new FileInputStream(file);

One solution is to return a 'lazy' file input stream that only opens the file when reading from the stream (and closing the file when the last byte was read). Maybe there is already a class (in Apache Commons maybe?) that can do that.