Support item.prop(PR_EC_IMAP_EMAIL) or add item.imap()

[jelly]

----> 1 foo.prop(PR_EC_IMAP_EMAIL)

/usr/lib/python2.7/site-packages/zarafa/init.pyc in prop(self, proptag)
1386
1387 def prop(self, proptag):
-> 1388 return _prop(self, self.mapiobj, proptag)
1389
1390 def props(self, namespace=None):

/usr/lib/python2.7/site-packages/zarafa/init.pyc in _prop(self, mapiobj, proptag)
130 def _prop(self, mapiobj, proptag):
131 if isinstance(proptag, (int, long)):
--> 132 mapiprop = HrGetOneProp(mapiobj, proptag)
133 return Property(mapiobj, proptag, mapiprop.Value, PROP_TYPE(proptag))
134 else:

/usr/lib/python2.7/site-packages/MAPI/Defs.pyc in HrGetOneProp(pmp, proptag)
43 if props[0].ulPropTag == proptag:
44 return props[0]
---> 45 raise Struct.MAPIError.from_hresult(props[0].Value)

MAPIErrorNotEnoughMemory: MAPI error 8007000E

this property needs to be streamed in, like the body as you can see here:
In [24]: stream = foo.mapiobj.OpenProperty(PR_EC_IMAP_EMAIL, IID_IStream, 0 ,0)

In [25]: stream
Out[25]: <MAPICore.IStream; proxy of <Swig Object of type 'IStream *' at 0x7f2bbc0ea5d0> >

It would be nice if item.prop() could handle this else we should implement item.eml().