Replace old-style feature gml:id values "ID_xxx" with "uuid.<UUID>"

AIXM Feature Identification and Reference 1.0, page 7:

| It is recommended that the gml:id of the AIXM features (such as
| aixm:Airspace, aixm:Runway, etc.) also make use of the UUID value,
| prefixed with "uuid.".

http://www.aixm.aero/gallery/content/public/AIXM51/AIXM_Feature_Identification_and_Reference-1.0.pdf#page=7
Convert all local references to abstract references
Add XSLT script to convert abstract "urn:uuid:" to local "#uuid." references
Convert LICENSE text to proper markdown and include it in README.md for better visiblity
Fix typos in update policy
Merge pull request #11 from m-click/use-abstract-refs

Use abstract references
Merge pull request #8 from m-click/replace-id-with-uuid

Replace old-style feature gml:id values "ID_xxx" with "uuid.<UUID>"
Merge pull request #13 from m-click/fix-typos

Fix typos in update policy
Use consistently the gml:id prefix "uuid." instead of mixing "urn.uuid." and "uuid."

AIXM Feature Identification and Reference 1.0, page 7:

| It is recommended that the gml:id of the AIXM features (such as
| aixm:Airspace, aixm:Runway, etc.) also make use of the UUID value,
| prefixed with "uuid.".

http://www.aixm.aero/gallery/content/public/AIXM51/AIXM_Feature_Identification_and_Reference-1.0.pdf#page=7
Fix indentation and add missing note for propertyName horizontalProjectionlocation
Merge pull request #10 from m-click/license-to-markdown

Convert LICENSE text to proper markdown
Merge pull request #14 from m-click/fix-propertyname-horizontalprojectionlocation

Fix indentation and add missing note for propertyName horizontalProjecti...
Merge pull request #15 from m-click/consistent-gml-id-prefix

Use consistently the gml:id prefix "uuid."
Fix UUID mismatch

There were two ways to fix this: Use consistently either UUID "c1bb..."
or UUID "5909...".

From the document it was pretty clear that "c1bb..." is the correct
UUID.  First, this unit is referenced by "c1bb..." at other places.
Second, there is already another feature with UUID "5909...".