REQS-382 - Add in Tenor class to basic finance
REQS-382 - Add in Tenor class to basic finance

Address PR comments
Rename constants
Serialized form can represent weeks
No 'P' prefix in serialized form0
REQS-382 - Add in Tenor class to basic finance

Address PR comments
REQS-382 - Add in Tenor class to basic finance

Address PR comments
Merge pull request #15 from OpenGamma/topic/REQS-382

REQS-382 - Add in Tenor class to basic finance