burst_buffer/cray work

Add new buffer state of "BB_STATE_PENDING"
Refactor job buffer state structure
Refactor job buffer creation environment
Rename "bb_hash" to "bb_ahash"
Set up job state hash table
Add magic cookies to data structures
Rename bb_find_job_rec() to  bb_find_alloc_rec()
Rename bb_free_rec() to bb_free_alloc_buf()