add ability to "get all" of every type of function that provides a *ByNextToken equivalent

[ericblade]

We should add a parameter to all the base functions that also have *ByNextToken versions, that will allow the MWS lib to go and gather up ALL of the data before accepting the promise.

So, you could potentially call something like

    callEndpoint('ListFinancialEvents', { GetAll: true })

and if you receive a NextToken with the initial result, then automatically call ListFinancialEventsByNextToken, and add that data to the original result. Re-run until there are no more NextTokens returned.

This is essentially what getReportListAll() does already.