Add SWD protocol support to buspirate (2nd try)

Add SWD protocol support to buspirate (2nd try)

This is a second try for this patch. I removed the queues from the
previous version. I made it compatible with SRST reset and added
support for those features that could be supported in raw binary
mode.

Change-Id: I96fc06abbea9873e98b414f34afd9043fd9c2a41
Signed-off-by: Mateusz Manowiecki <segmentation@fault.pl>
Reviewed-on: http://openocd.zylin.com/3960
Tested-by: jenkins
Reviewed-by: Eric Work <work.eric@gmail.com>
Reviewed-by: Thomas Jarosch <thomas.jarosch@intra2net.com>
Reviewed-by: Jacob Alexander <haata@kiibohd.com>
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>