Fix libnl/libnl-3 logic in configure script

This patch causes the configure script to prefer libnl-3 over
libnl(1). The configure script will first check for libnl-3 and
libnl-genl-3. If both are found, use them. If not, check for
libnl(1). This is useful when building on systems that have both
libnl-3 and libnl(1) installed. It also fixes some redundant libraries
in LIBS.
Merge pull request #65 from rohara/devel

Fix libnl/libnl-3 logic in configure script
libipvs: libnl-3 include fix

when libnl-3 is present use proper include path. On most system libnl-3
include path is /usr/include/libnl3.
lib: extend command lib string parser

Extend cmd_make_strvec to support quoted string as a single slot and
commented string at the end of parsed string.
lib: cosmetics at command.c

Extend command framework to support logger and remove some dead code.
some cosmetics too.
lib: extend vty to support logger

add support to logger and some cosmetics.
autoconf: better libnl3 detection

use pkg-config facilities to append CFLAGS related instead of hardcoding
libnl3 path in configure script.