v0.0.3

Merge pull request #3 from ClearcodeHQ/add-xml-tag-to-duration

add xml tag to Duration

v0.0.2

Some additional structures were adjusted to order required by IAB's .xsd.

v0.0.1

Order of VideoClicks struct now corresponds to the order defined in IAB's .xsd file.
'xmlns' attribute was added to VAST struct so it can be validated with IAB's .xsd file.