Add element to handle one-off item type in Plimpton.

In the George Plimpton collection, item 33 has the following:
<item_-_ItemType_1>Original Format: book</item_-_ItemType_1>
<item_-_ItemType_2>Physical Dimensions: 21 x 16 cm</item_-_ItemType_2>

The above is not really an item type, and it has to be handled
differently according to the CUL mapping specs. Since the above
is the only occurence in all the collections that have been processed
so far, two instancses of a new, Plimpton-specific element will be added
to the Plimpton prepped remediated metadata, and code will be added
to the XSLT stylesheet to handle this very specific case
Change code to handle one-off elements in George Plimpton

To handle the one item in the George Plimpton collection that
has Original Format and Physical Dimensions information, new
elements were added to the prepped remediated metadata
(see commit d10e257ea06d118da721ea31b73b4df414c93b87) and
this commit was used to add the processing of these new
elements to the XSLT code.
Regenerate MODS due to commits listed below:

d10e257ea06d118da721ea31b73b4df414c93b87 and
10ba052cd04da420d10a12e684bb3b27af05f846