interfaces: bond listening was broken only for old kernels

With a recent kernel, we can listen to individual member. lldpd is still
listening on master to keep compatibility with older kernels and because
it is difficult to detect if the kernel gives us this ability or not. We
can't rely on version numbers as some kernels have backported
features (like 2.6.18 from RHEL 5).
debian: update symbols file
systemd: fix systemd unit file

@sbindir@ was not properly replaced.
lldpcli: pretty print json

Signed-off-by: Kanna Rajagopal <kanna@cumulusnetworks.com>
client: fix configuration modification

Handling of configuration change was messy. Whatever configuration item
needed to be updated, a whole lldpd_config structure was sent. The
daemon part was trying to guess what changed by assuming non-0 fields
need to be updated. However, when flags were added, the implementation
became inconsistent. Some flags used 1/2 for true/false, some others
kept 0/1. So, some flags were detected as changed while they were not.

Since we require to provide a current configuration before making any
change, we just copy the whole structure, modify what we want and send
it to the daemon. The daemon will then compare the new structure with
the old one to detect changes. Flags that were using 1/2 logic are now
just using 0/1 like others.
lldpd: use strdup() on arguments that could be changed by lldpcli

And add the appropriate "const" modifier for those that don't. The
compiler should warn us if we did something wrong.
build: hide renaming of template-generated files
NEWS: add an entry about some flags not being persistent accross time

See e4c51716848a639daf61eff3e96ad242af3e316b.
lib: factor out some code in `_lldpctl_atom_set_str_config()` in a macro
lib: replace macro by a function for `_lldpctl_atom_set_str_config()`
lldpcli: allow to unset patterns and system description/hostname
lib: document the possibility of using NULL with `lldpctl_atom_set_str()`
lib: make it safe to pass NULL to `lldpctl_atom_set_str()`

Even if we don't allow such a thing.
lib: bump versioning

Even if the ABI stays the same, the ability to pass NULL is an interface
change (backward compatible). We don't want new versions of lldpcli to
interact with an old version of the library.
debian: update symbol versioning for incompatibility of `lldpctl_atom_set_str()`
travis: travis comes with autotools and friends already installed

If they are not quite up-to-date, we get an error, so don't try to
install them.
client: fix "update" command

Commit e4c51716848a639daf61eff3e96ad242af3e316b broke this command
because we were checking for `tx_hold` instead of `tx_interval`. Let's
fix that.
lib: fix pkgconfig file substitutions
release: prepare release of 0.7.12
redhat: requires pkg-config to build devel package

This is not really needed but SuSE is a bit picky in their checks.