db changes and added tests based on requirements

Since we're already totaling transactions (since there's no date
dimension), I added customers without transactions to the Transaction
cube.  This should make the Customer cube mostly unnecessary.  I still
have to figure out how to get sorting to work consistently and possibly
how to filter out zero revenue amounts when they aren't wanted.

The tests are based on the requirements, but I'm not sure exactly what
the professor meant by "all or individual" in each case.  We probably
have some room to interpret it and should consider how we want to
display each type of data and what interactions we want to enable.

Will need to add a loading indicator for larger datasets.

Other things to consider: subtotals, suppressing consecutive dimension
descriptions (in html or css), columns order for hierarchy (on database
side), parameterizing filtering on dimensions (on server side).