added example xml document

it won't validate until we merge issues #2 and #3
changed place id from PLA_... to PLC_...

in accordance with [the spreadsheet](http://tinyurl.com/nwdl5tl)
removed "Crises" element
make the "Place" element optional

since we're not graded on this we should make it an optional thing to
include in the xml.
Merge pull request #2 from aaronj1335/correct-place-id-regex

changed place id from PLA_... to PLC_...
Merge pull request #4 from aaronj1335/make-place-optional

Make place optional
Places unbounded per crisis