Provide a better way to signal errors

[lazywithclass]

Right now we are failing with something like

TypeError: Cannot call method 'toString' of undefined
      at Jedlik.query (/home/developer/src/elemez/node_modules/jedlik/index.js:26:120)

and it should be (for example)

MissingParameter: hashkey expects the name of the column

if it was called like this: new Jedlik().hashkey('KEY-VALUE') and not like this new Jedlik().hashkey('KEY-NAME', 'KEY-VALUE').