Install Openocd

[anuejn]

It would be nice if openocd would be installed by default in the automatically installed builds since it is very handy for flashing the usb3 plugin modules (on the micro).
The sysfs bitbang driver needs to be enabled so a custom build is nescessary.

[herbertp]

We probably want to include any driver required for the kernel interface (or direct pic access) as well.

[rroohhh]

Installing openocd is done in #174, still needs pic driver.