Decide policy regarding "write queries".

[danibishop]

We need to decide if it is 100% up to the user to decide if chache must be used in every specific case or if we try to define a default behavior depending on how the query looks. There is already a ticket regarding this at #20

[josemazo]

On second thoughts, I think the best behavior could be don't cache any query, and use it if the method says so. The developers should be responsible if they cache a write query... maybe it's the behavior they want.