Offboard control fix

We we're having some issues with offboard setpoint control and eventually tracked it down to here.  The code was ignoring yaw and yaw rate masks due to improper bit shifting.  

Navigator was also repeatedly publishing invalid setpoints, which would drown out valid setpoints coming via mavlink.

I'm not sure if these fixes align with best practices - I'll let someone else be the judge of that.  

In any case, this fixed our issues and hopefully this helps someone else.  
The first bitwise AND (mask & (1 << 10), results in bit 10, then the second shift is applied by OFB_IGN_BIT_YAW (which is 14, in uORB offboard_control_setpoint), and shifts bit 10 14 places left, instead of shifting it to bit 14.  Shifting the bit 4 places puts it in the correct spot, but it is a little mystical.  Tried a readability fix in latest commit.

Also, the code above for bits 0-8 make the assumption that OFB_IGN flags in uORB match the bit structure in the mavlink message.   Which looks cleaner, but could be a tricky bug if either definition changes.