Use user's prefered shell instead of hardcoding bash.
Use user's prefered shell instead of hardcoding bash.

the SHELL environment variable is specified by POSIX[1] to represent the
absolute path to the user's preferred command language interpreter,
which is what we want here.

[1]http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03

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