added column 'public_url'

database migration sql:
ALTER TABLE chart ADD COLUMN `public_url` VARCHAR(255);
store public url in chart table during publication
use public_url in iframe code
refactoring s3 publish module to enable custom endpoints
using public_url in chart html
keeping old sessions a little longer
refactored chart publication
creating chart thumbnails during editing
nodeValue is deprecated
renamed dw.ui to dw.utils
version --> 1.2.9