Catch ipw2200 up to equivelancy with v1.0.1

This commit contains the following fixes:

Fixed #559: iwconfig rate support (thanks to Florian Hackenberger)

Improved link signal quality calculation (thanks to Bill Moss)

Fixed a problem with sensitivity threshold during association

Added iwpriv for turning forcing long preamble support:
  % iwpriv eth1 set_preamble 1|0

Fixed #542 and #377 support for short preamble

Fixed locked BSSID reporting channel number (thanks to Pedro
Ramalhais)

Fixed type-o with scan watchdog timeout message (thanks to Pedro
Ramalhais)

Changed logic for displaying get_mode output so the code is easier to
follow (thanks to Pedro Ramalhais)

Added initial support for WPA (thanks to Yi Zhu) -- tested with
wpa_supplicant (either tip w/ ipw driver, or with -Dipw2100) with
both CCMP and TKIP

Fixed problem with CCMP not working due to uninitialized 802.11
header fields (thanks to Pedro Ramalhais)

Bug references are to defects stored on http://bughost.org

Signed-off-by: James Ketrenos <jketreno@linux.intel.com>