Code review comment for lp:~meths/openlp/trivialfixes

Initial information:

Fixes logging issue found testing Impress presentations.
Problem: sys.exc_info() is an array and passing it as a whole doesn't work.
Solution chosen is to eliminate the log.error() sys.exc_info() combination completely in favour of log.exception()

Addressing TRB's issues:

1- Less information provided:

Okay I've fudged a comparison by forcing the plugin to try and load powerpoint and powerpoint viewer when neither are installed. Top section is the information given in a log exception, bottom line is information from the log error:

2009-09-18 12:43:14,010 PresentationPlugin ERROR Failed to setup plugin for Powerpoint
Traceback (most recent call last):
  File "D:\Projects\OpenLP\openlp\trunk\openlp\plugins\presentations\presentationplugin.py", line 97, in check_pre_conditions
    powerpoint = PowerpointController()
NameError: global name 'PowerpointController' is not defined

2009-09-18 12:43:14,010 PresentationPlugin ERROR Reason : (<type 'exceptions.NameError'>, NameError("global name 'PowerpointController' is not defined",), <traceback object at 0x0387A670>)

2 - Should only be called from an exception
The diff should confirm the only ones I've changed occur in except: branches when we have a problem.