Update OME-XML population to match 2013-06 changes

```BigEndian```, ```Interleaved```, and ```SignificantBits``` on ```Pixels``` should be populated for all files; ```BigEndian``` on ```BinData``` (under ```Pixels```) should no longer be populated.

```NominalMagnification``` should never be cast to int before being passed to ```MetadataStore```.