first cut at attrs -> metadata
Add conversion from state_id to metastable_id
change docs to reflect state_id vs. nuc_id split
update nucname docs
refactor nuc_id to id and add generator
Merge pull request #423 from scopatz/metadata

Moved material attrs to metadata
Merge branch 'midtostate' of https://github.com/crbates/pyne into crbates-midtostate
Merge branch 'crbates-midtostate' into staging