Changed SesXMLWriter to use the rupture tag
Fixed the writer tests to use the rupture tag
Fixed the SESXMLWriter to save the ses.ordinal, not ses.id
Fixed the case when the ordinal is None
Fixed the case when the ordinal is None (again)
Merge pull request #109 from gem/rupture-tag

Ruptures now have a tag attribute
Merge branch 'master' into node-library
Fixed copyright
Merge branch 'node-library' of github.com:gem/oq-nrmllib into node-library