Pillar values:
linux.monitoring.bond_status.interfaces = [ 'bond0', 'all', 'etc' ]

Leave bond_status.interfaces undefined to disable (default).

Depends-On: Ia07d4c473bf64d98170f51599caaedb46645ede3

Change-Id: I62a7d59251d37cb6c7fc7b761f63a5599930f1dc

This is typically used to mount Docker containers but it generates too
many volatile metrics which aren't useful.

Change-Id: I00117895570515b2c8f9690542e83061309464c3

The `linux_netlink.ls` function used a regex to choose which interfaces
to collect metric for.

`_alphanum_re = re.compile(r'^[a-z0-9]+$')`

Unfortunately, by default this excludes vlan and tap interfaces, which
are kind of important.  ie `bond0.120` or `tap2a3dab86-fb`.

We also have a problem where even if we update the regex to include
these interfaces... if someone deletes and spawns a new instance then
the tap device name changes on the compute host, which will not be
monitored unless someone re-runs the `collectd` on the compute again.
Less than ideal.

This commit lets us choose `VerboseInterface "all"` using Pillar data
to avoid this problem.

Change-Id: Id4b0b405872457bd8b20f450e4031d6808d3cf59

Change-Id: Ic39fa0f18e0d9aeca0ef73ae6d985d12d15a1c3a

This is to comply to a comment from @cznewt in
https://github.com/tcpcloud/salt-formula-heka/pull/24.

This patch replaces the "interface" collectd plugin by the "netlink" one. The
"netlink" plugin provides the same metrics as "interface" but plus other
metrics such as the number of dropped packets.