pynipap - Pylint; Line too long

Cut of a few lines that were too long. There's a bunch of lines that are
still too long, but they are typically exception lines with a message
and I don't see that the code is more elegant with them cut off.

Pylint score was originally 7.28 and is now up to 7.34

Part of #274
pynipap - Pylint: Unused import ...

Removed two useless import statements.

Score 7.34 -> 7.37

Part of #274
Improve pynipap exception handling

The pythonesque way to name exception is using "as" and not appending ",
<name>". Code is updated to reflect that.

If we don't need the exception object, we don't ask for it and exception
object for XML faults is now called 'xml_fault' instead of 'f' to comply
with Pylints minimum-3-character-variable-length.

Pylint score 7.37 -> 8.04

Part of #274
Merge branch 'master' of github.com:SpriteLink/NIPAP