NEW: Add dependency status badge.
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
Merge pull request #61 from amercader/master

NEW: Add support for multiple facet.field values
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
Merge branch 'master' into gh-pages
NEW: Update docs for the version 0.2.7.