Fixes Bug 929198 - made sure that truncation gets copied from the json_dump

the older versions of the processors all did the stack frame truncation themselves and placed a boolean "truncated" key in the top level of the processed_crash.  

The new stackwalker now does the truncation of abnormally long stacks.  It places its own 'frames_truncated' boolean in the json_dump at the thread level.  We still need to make sure that the old 'truncated' field gets an appropriate value.