Fixes issue with serial port logging availability

If the configured serial port is not available logs the exception
instead of causing the program to terminate.
Merge pull request #77 from trobert2/first_refactor3

Modified test_x509.py osutils/test_windows.py and test_log.py to work on Linux
Replaces s.unicode with six.text_type

six.text_type() provides already the feature provided by s.unicode().
Adds a serial logging wrapper for unicode strings

Adds a filter in the serial port logging handler to convert unicode
string input to bytes as pyserial does not handle unicode content.
Use bytearray.fromhex instead of binascii.unhexlify.
Merge pull request #80 from trobert2/test_refactor4

Modified osconfigdrive/test_windows.py to work on Linux
Merge pull request #79 from PCManticore/master

Use bytearray.fromhex instead of binascii.unhexlify.
Fixed osconfigdrive test errors