openocd: bump from 0.4.0 to 0.6.1

Also:
 * Remove commented out "GuruPlug installer" stuff that hasn't worked
   since openocd 0.2.0 (according to the comments).
 * Build with support for the following JTAG hardware:
   - Segger J-Link
   - Raisonance RLink
   - Keil ULINK
   - STMicroelectronics ST-Link
Merge pull request #308 from bjornfor/master

openocd: bump from 0.4.0 to 0.6.1