Merge pull request #5 from doodles526/working

terminated XMLName from appearing in json
Merge pull request #6 from doodles526/working

added json omitempty tags
feat(omaha): add Track field

this is another update_engine extension. Add it.
chore(omaha): group the update engine extensions together
Merge pull request #7 from philips/add-track-extension

Add track extension
added isActive field to App
Added IsActive field to app.