Add proper less to image (disable busybox less)

The version of less in busybox is quite annoying when working on OpenELEC. It doesn't properly support searching in files or tailing (and interrupting) logfiles. It also doesn't properly handle non-ascii characters. This patch disables busybox less and instead adds the latest stable less release.
Replace busybox free with *real* free from procps-ng

Busybox free reports incorrectly the used and free memory on a system. Which makes it harder to understand and compare information from other sources.

In the same effort we add some other useful procps-ng tools, like pgrep, pkill, pmap, slabtop, vmstat and watch.
less: depends on ncurses, run autoreconf, cleanup

Signed-off-by: Stephan Raue <stephan@openelec.tv>
procps-ng: enable autoreconf, cleanup

Signed-off-by: Stephan Raue <stephan@openelec.tv>
procps-ng: update to procps-ng-3.3.7

Signed-off-by: Stephan Raue <stephan@openelec.tv>