PLT-466 - Refine definition of Frequency and Tenor

Use months when less than 24 months and years above that
Unify definition of 1 year to be 12 months
Extra tests
PLT-466 - Refine definition of Frequency and Tenor

Retain distinction user chose between months and years
Add normalized() method
Extra tests
PLT-466 - Refine definition of Frequency and Tenor

Parse 'Term' case insensitive
PLT-466 - Refine definition of Frequency and Tenor

Fix schedule GUI
PLT-466 - Refine definition of Frequency and Tenor

Use constants for large values
PLT-466 - Refine definition of Frequency and Tenor

Remove unecessary ability to create TERM period from 10,000 years
PLT-466 - Refine definition of Frequency and Tenor

Fix Javadoc
Merge pull request #25 from OpenGamma/topic/PLT-466

PLT-466 - Refine definition of Frequency and Tenor