ExifInterface: keep the original metadata data instead of strings

This CL makes ExifInterface store the tag values as the original forms
and the format validiation is added that compares the given value and
the data format specificed in EXIF specification in order to keep the
valid tag values only.

Bug: 27583378, Bug: 27614052, Bug: 28075709
Change-Id: If60bbddefe74c4b87b4ce64b5fc79e467e36a5b9
6 files changed