*/iojs-*: make sure all have the ENVs correctly

This way we can avoid a lot of issues with DEBIAN_FRONTEND trying to get
interaction while updating/installing something and the LC_ALL from
failing somehow.
iojs-*: cp -a into /build/iojs to avoid permission issues

If the build is executed directly in the mounted host-volume then it
will fail if the user on the host machine is not the same than the user
in the container (which is most likely true all the time).

Plus, this way we avoid to leave executables on the host-machine. They
are built on the container and removed with the container when the
container ends building it.
libuv-*: making sure LC_ALL and DEBIAN_FRONTEND are set
libuv-*: cp -a to /build in order to avoid permission issues
libuv-*: fix typo /build/iojs -> /build/libuv