NEW: Added support for facet range queries
FIX: Added support for zero values in facet range queries
NEW: Added stats support
FIX: Fixed type in setting stats facet param.
Add support for multiple facet.field

The facet.field parameter can be specified multiple times to indicate
multiple facet fields [1]. This patch provides support for passing an array
instead of a string on the `field` key of the `query.facet` method
options, eg:

    query.q({'*': '*'}).facet({'on': true, 'field': ['title', 'year']});

as well as:

    query.q({'*': '*'}).facet({'on': true, 'field': 'title'});

[1] http://wiki.apache.org/solr/SimpleFacetParameters#facet.field
FIX: Remove node.js versions: 0.4 and 0.7 from travis conf

these version are not installed anymore on travis
FIX: Update development dependencies to the latest versions.
NEW: Add node.js version 0.10 to travis conf.
NEW: Add as dev dependencies csv-stream module to showcase the client#createAddStream method.
NEW Showcase the client#createAddStream method.
FIX: Update module dependencies to the latest versions

These dependencies are used exclusively by the client#createAddStream method.
NEW: Add npm stats logo.
NEW: Support multiple group fields

Close #62x
FIX: Change the field cat by description, a field available by default in a Solr database.

The default configuration does not provide the field cat so the test fails against a real Solr database with the default configuration.
FIX: Indent correcly and remove trailing spaces.
FIX: Update the request module to the latest version published 2.27.0
FIX: Remove console.log.
RELEASE: v0.2.7
NEW: Extend createClient params with agent

One can pass a new http.Agent or false to overwrite the default
globalAgent used by http.request
FIX: Only set agent if it is set

This change allows to make thing clearer about the fact if the agent specified is used
or not, even if the default behavior of the http.request is to used the
http.globalAgent while the agent given in options is "undefined".

(from the official doc undefined (default): use global Agent for this host and port.)