Ensure all helper scripts pushd/popd

Make sure all of these move to the root of the repository first, then
return to where they were afterwards, using pushd/popd. This allows them
to be executed from anywhere in the repo.

gen-api-migrations

@@ -4,8 +4,10 @@
 
 VERSION="$( head -1 debian/changelog | awk -F'[()-]' '{ print $2 }' )"
 
-pushd api-daemon
+pushd $( git rev-parse --show-toplevel ) &>/dev/null
+pushd api-daemon &>/dev/null
 export PVC_CONFIG_FILE="./pvcapid.sample.yaml"
 ./pvcapid-manage.py db migrate -m "PVC version ${VERSION}"
 ./pvcapid-manage.py db upgrade
-popd
+popd &>/dev/null
+popd &>/dev/null