Fix overlapping memcpy() in WDL_PtrList::Delete()

The memmove() function must be used when memory ranges overlap.  Some C
standard library implementations take advantage of this constraint and
the data can be corrupted if memcpy() is used.

Signed-off-by: Stefan Hajnoczi <stefanha@gmail.com>
Drop format=xml from JammrUserLookup HTTP request

The jammr REST API has been using JSON for some time now.  The
format=xml query argument was a left-over from the old XML REST API.
Luckily the new REST API always emits JSON so this never caused
problems.

Signed-off-by: Stefan Hajnoczi <stefanha@gmail.com>