Install git-ssb on mesh

src/freedombone-image-customise

 npm install --arch=$NPM_ARCH --build-from-source
 npm install --arch=$NPM_ARCH --save-dev electron-rebuild
 ./node_modules/.bin/electron-rebuild
+npm install --arch=$NPM_ARCH git-ssb
 EOF
     chroot "$rootdir" /bin/chmod +x /usr/bin/install_patchwork
     chroot "$rootdir" /usr/bin/install_patchwork