added check digits for PI generation.
Merge remote-tracking branch 'origin/master' into check-pi
updated PI check digits util.
added getObjId() method.
added struct map for creating structures within the graph model using strategy pattern.
added libray api to support items files ingest.
added a stage area for checking items' metadata and struct map (re: banjo #130) before ingest.
updated ingest apis.
tidy up frames classes.
updated ingest apis.
2nd draft of ingest api.
added test to verify a work can be found by its PI from amberdb.
Merge pull request #5 from nla/check-pi

Check pi