Fix bug multiple filters return no results multipleRange and others

[Mrkisha]

When Filter is used to fetch data, redis returns no results if filter params is not array.

[palicao]

Thanks @Mrkisha, very good catch!
There is a problem: the function Filter::toRedisParams() is also used in 2 other places (TimeSeries::getLastSamples() and TimeSeries::getKeysByFilter()), you should update it also there and prepare the arguments using array_merge().
Also it would be great if you could also write the related integration tests (otherwise I'll do it later, no problem!)

[palicao]

Those are not needed, apart from the first, all the other parameters have default value = null.

[Mrkisha]

I wanted to be explicit about it. But I'll remove it.

[Mrkisha]

Thanks @Mrkisha, very good catch!
There is a problem: the function Filter::toRedisParams() is also used in 2 other places (TimeSeries::getLastSamples() and TimeSeries::getKeysByFilter()), you should update it also there and prepare the arguments using array_merge().
Also it would be great if you could also write the related integration tests (otherwise I'll do it later, no problem!)

I've took care of these in tests. Check TimeSeriesTest tests.

[palicao]

@Mrkisha the problem is that TimeSeries::getLastSamples() and TimeSeries::getKeysByFilter() will break if we merge those changes.
I am creating a branch which fixes the problem in the whole library.

[palicao]

Closing because solved in #3