Null check for threshold property in TopN query

Fixed the issue #53

Support for DataSketches

DataSketches are available as an extension :
http://druid.io/docs/latest/development/extensions-core/datasketches-aggregators

This release includes DataSketches related Aggregators and Post Aggregators.

Aggregators:

1. thetaSketch

Post Aggregators:

1. Sketch Estimator (thetaSketchEstimate)
2. Sketch Operations (thetaSketchSetOp)

Equals And Hashcode for all entities and Builder for DruidSearch Query

1. Now 2 queries and their components would be considered equal if their values are equal. Equals and Hashcode functions are overridden. (#14)
2. Builder for DruidSearchQuery is added. (#44)

External Contributors:

1. Harikrushna V (@hgvanpariya)

IntervalFilter Fix

1. Bug where the type wasn't being set while creating of the filter. (#35)
2. Not allowing null values in the constructor
3. Unit Test case for the same.

Critical Bug Fix for getting List of Casted Object while querying

public <T> List<T> query(DruidQuery druidQuery, Class<T> className)

The method used to return as LinkedHashMap and not as T, which is asked.
From now, it will respect the class passed.

Contributor for this patch:

1. Yeh-lei Wu (@aylei)

Support for Builder and Setter in Bound Filter

Merge pull request #29 from zapr-oss/develop

Version bumped to 2.1

Druidry as a Client

Druidry has evolved from a query generator to a Client.
With Druidry, the developer doesn't need to handle connections to the brokers and serializing and deserializing. Druidry takes care of that.
It uses Jersey as a client.

Although it is a major version upgrade, backward compatibility is still maintained. You can upgrade without any hassles.

Equals and Hashcode overrides for Interval class

Merge pull request #18 from zapr-oss/develop

Releasing Druid Client and version bumped to 2.0

Period Granularity was made child class of Granularity

Merge pull request #8 from zapr-oss/develop

Adding support for travis