This simple fix solves "no such file or directory" error when user
home directory is not prefixed by /home.
This is the case, for example in devstack, where stack user home is
set to /opt/stack/.
Lets use $HOME variable to determine user home location.
Change-Id: I07432d27e1a2035296bc62793fecbe13d0265e7b
Signed-off-by: Marcin Piwowarczyk <m.piwowarczy@samsung.com>