Fix error when raising without an Exception.

Raising without a valid exception is invalid:

>>> raise
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: exceptions must be old-style classes or derived from BaseException, not NoneType
>>> raise Exception
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
Exception

Changing this to "raise Exception" fixes this problem.
PyNUT: Create a custom exception class.

This maintains backwards compatibility, and allows calling programs to
use "except PyNUTError" instead of "except Exception" when using PyNUT
methods.

See https://wiki.python.org/moin/HandlingExceptions for more
information.
Change format of raise keyword.

Fixes PyNUT Python 3 compatibility.
Added author information, bumped version.

According to the semantic versioning scheme (http://semver.org/), adding
features that do not break backwards compatibility with previous
releases means that the minor version number should be incremented.
Fixed version description.
Minor update and completion

Use the new Debian package tracker URL and add Redhat / Fedora bug
tracker
genericups: log cable type overrides as they are parsed

Fixes networkupstools/nut#28

Better than nothing, but without a unit to test against, I don't want to make
any more intrusive changes.
Fix compliance of NUT-Monitor FreeDesktop AppData file

Following the upstream update (by David Goncalves), update the
screenshots width and height to conform to AppData specification:
http://people.freedesktop.org/~hughsient/appdata/

Closes networkupstools/nut#127
tripplite_usb: fix voltage scaling for 240V/1001 (0.28)

Reported by Dave Williams:
http://article.gmane.org/gmane.comp.monitoring.nut.user/8713

The input.voltage and output.voltage scaling for Protocol 1001 did not factor
in the input_voltage_scaled value.
tripplite_usb: scale min/max voltages for SMART protocol (0.29)

Observed in a dump file from driver version 0.11. Scale input.voltage.minimum
and input.voltage.maximum the same way as other voltages.
HCL: add Tripp Lite OMNIVSINT800 (tripplite_usb)

Source: http://article.gmane.org/gmane.comp.monitoring.nut.user/8713
HCL: sort Tripp Lite models by name, then increasing power

I know this doesn't allow the cell merging code to do as much, but this should
make it easier to find models.
Merge pull request #129 from rshipp/python3

PyNUT: Python 3 support and better exception handling
Make ltrim() modify the input string

Also, always check string length in both ltrim() and rtrim().

Reference: https://github.com/networkupstools/nut/issues/154
Add ltrim_m()/rtrim_m() functions to trim several chars at the same time

Also, make ltrim() / rtrim() wrappers around ltrim_m() / rtrim_m().
nutdrv_qx: move to ltrim_m()/rtrim_m() functions