dahdi_scan: Support gaps in channel numbering.

If, via the sysfs attributed introduced in DAHDI-Linux 2.5.0, a user has
configured spans that do not have contiguous channel numbers, dahdi_scan will
not print several of the span attributes in addition to a bad basechan number.

This patch allows dahdi_scan to try and get the basechan for a span from sysfs
as opposed to calculating based on the number of channels in the previous span
scanned.

Signed-off-by: Shaun Ruffell <sruffell@digium.com>
Ignore generated files

Signed-off-by: Tzafrir Cohen <tzafrir.cohen@xorcom.com>
Signed-off-by: Russ Meyerriecks <rmeyerriecks@digium.com>
Don't fail init script if no modules

No point in loading the modules if nobody built them yet. It is a common
case for one to install the userspace tools package but not (yet?) build
the modules. See, e.g.  http://bugs.debian.org/706046 .

With this changeset, we exit gracefully in such a case.

Signed-off-by: Tzafrir Cohen <tzafrir.cohen@xorcom.com>
Signed-off-by: Russ Meyerriecks <rmeyerriecks@digium.com>