Fix build.sh to use bash and rm -f
Fix build.sh to use bash and rm -f

build.sh uses pushd/popd but is coded with /bin/sh; at least some
/bin/sh's don't support that.  Also, rm jsonview.zip fails if
the file doesn't exist; rm -f fixes that.

Fixes: https://github.com/bhollis/jsonview/issues/160
Signed-off-by: Dan Mick <b07550071eaa6a9296289c43bbd6c90559196431@redhat.com>

bhollis/jsonview,bhollis/jsonview,bhollis/jsonview