Handle log file errors more gracefully

[Andrew Garner]

If the log file can't be written (maybe the directory is missing or we don't have permissions, etc.) holland should handle that gracefully - either aborting or just continuing on with a log file.

File "/usr/lib/python2.4/site-packages/holland/core/backports/logging/__init__.py", line 749, in __init__
stream = codecs.open(filename, mode, encoding)
File "/usr/lib64/python2.4/codecs.py", line 666, in open
file = __builtin__.open(filename, mode, buffering)
IOError: [Errno 2] No such file or directory: '/var/log/holland/holland.log'

[Andrew Garner (muzazzi)]

IOErrors when opening log files are now treated as non-fatal and file logging will simply be skipped.