Force use of /bin/echo to in s3init
Force use of /bin/echo to in s3init

In some sh implementations, echo is a builtin command without support
of the `-e` and `-n` options. But `/bin/echo` does implement them.

Specifying `/bin/echo` directly will ensure that s3init will work with any
sh implementation.

jimconner/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,jimconner/paas-cf,alphagov/paas-cf,jimconner/paas-cf,alphagov/paas-cf,alphagov/paas-cf,jimconner/paas-cf,jimconner/paas-cf,jimconner/paas-cf,jimconner/paas-cf,alphagov/paas-cf