Update App.run for docker 0.7 and slugrunner syntax

[gabrtv]

Please note this must be merged along with docker 0.7 cookbook changes.

[coveralls]

Coverage remained the same when pulling ac26eb7 on docker-0.7 into 9f18138 on master.

[coveralls]

Coverage remained the same when pulling 2e47a14 on docker-0.7 into 9f18138 on master.

[coveralls]

Coverage remained the same when pulling bf3a57d on docker-0.7 into 9f18138 on master.

[coveralls]

Coverage remained the same when pulling 362f95b on docker-0.7 into 9f18138 on master.

[mboersma]

This is all working well in my testing. Merging at 1900 MST unless @gabrtv objects.