Added new elements, removed redundant

The initial schema I created was before the requirements were posted, so it contained several sample elements like <Place> and <PlaceID>, as well as sub-elements like <Born> and <Office> for persons, etc. I've cleaned these up and added elements exactly as mentioned in the requirements on the project page.

Additional changes:
- Removed Place container type and PlaceID completely, since it adds to complexity and isn't a requirement. Replaced it with a list of plain-text "locations" that are a sub-element of <Crisis>
- Added Keys and keyrefs for all three types (Crisis, Person, Organization).
- Added three new types: CrisisWithID, PersonWithID, OrgWithID to contain these keyrefs as attributes, specified using xpath.
- In addition to <Crisis> containing related Orgs and People, <Organization> needs to contain related Crises and People, and <Person> needs to contain related Crises and Orgs. This is because each of these relations are many-to-many.
- Added all other elements under <Crisis>, <Person> and <Organization> mentioned on the project page. All sub-elements except references to Crises, Orgs and People now have minOccurs=0 to allow missing values.
- Added an <any> element at the end of all three containers to allow extra elements to be added in XML.
- Added a <ListType> container, in which each element can contain optional hyperlinks, embed links as well as plain-text (text to be displayed on page). This is meant to be a generic data type that can accommodate all kinds of data.
- Added a <Common> type container, which contains elements common to Crises, People and Orgs {Citations, External Links, Images, Videos, Maps, Feeds}, each of type ListType.
- Attempted to create a standard for storing URLs for embedded objects (images, videos, maps, feeds) in the elements of ListType, considering the inability of ElementTree to read [!CDATA.. or mixed content. See comments on example XML for details.

I also had to write the example XML from scratch because I didn't have any other sample data for all the new fields..

These are a lot of changes, and all are open to discussion. Let me know what you think.
Sorry for making all changes in one go.. if anything needs to be modified I can commit on top of this.