The assets building - e.g. npm and bower installation followed by build task -
must be done in the build sequence instead of the install one. The main reason
is logic, we are building something. The second one - which we "fixed" by
adding extra arguments to npm and bower - is due to the user who runs those
sequences: *build* uses a non-privileged one while *install* uses root. It
resulted in npm and bower complaining about using the root user.
Since 03e979f, bower installation is integrated to npm postinstall, that's
why this issue reappears. This commit also removes the useless `bower install`
command.
