Major change was to add Stocks for the Portfolios.  Totally random now and all data (portfolios and stocks) is random / nonsensical.  POC.  Specifically:

1. Updated Portfolio entity and added a Stock entity and added a @ManyToMany relationship between them.  Using Observable
2. Updated PortfolioController to display the data including upon a change (ie. different portfolio selected)

TODO:
1. Change StocksInPortfolio and v-v types to ListProperty as believe that is what I'm actually looking for so can bind both ways.  I've really got to test if this is necessary.
2. PortfolioController is getting a bit big.  Look at ways of making more cohesive by splitting out into other classes.  Investigation required.