As per bug #472104 add option --verbose-slot-rebuilds=y|n
Whitespace cleanup
man/ebuild.1: Add --verbose-slot-rebuilds option.
portage/emaint/main.py: Fix a bug in the options parsing.
man/make.conf.5: Fix misinformation (bug 504532)
ebuild-helpers/xattr/install: use the binary wrapper if available; fall back to the python one

Signed-off-by: Gregory M. Turner <gmt@be-evil.net>
xattr/install helper: put /usr/bin at front of path to avoid invocation-bomb

Signed-off-by: Gregory M. Turner <gmt@be-evil.net>