Fix misplaced backslash in start template
Fix misplaced backslash in start template

During a recent refactor a backslash intended to be an end of line
escape was inadvertantly placed into the middle of a line when a
container command is specified. This fix reinserts the newline the
slash was meant to escape.

Fixes #661

puppetlabs/puppetlabs-docker,puppetlabs/puppetlabs-docker,puppetlabs/puppetlabs-docker