Changed job_id to 32 bits per DPCS requirement. Jobs without job_id

specified at submit time start with a value of 1<<16 and DPCS uses
values 1 to 0xffffffff. This preclude effective use of a max job_id
in search function, which was able to quickly indicate that a job_id
requested by DPCS was not already in use. I added a job_id hash table
to restore quick job find operations.
Added check of packstr function to insure string would not go over
64k bytes, which is the limit for the protocol used.