remove chrome and cordova targets for the time being

it would be nice to have these again in the future, but at the moment
we should concentrate on how to deliver assets in a browser environment.

when we add it again, it would be nice to externalize the tasks so
the main gulpfile isn't cluttered with details regarding these targets
Merge pull request #41 from DataSplice/remove-chrome-cordova

remove chrome and cordova targets for the time being