1) Expanded Grouping Query to include multiple queries (For example: http://localhost:8983/solr/select?wt=json&indent=true&fl=name,price&q=memory&group=true&group.query=price:[0+TO+99.99]&group.query=price:[100+TO+*]&group.limit=3)

2) Added a Test on Grouping Query
Corrected a copy/paste mistake on class being renamed.
BUGFIX: Added check for null on group.field and group.query.
Update Sample-application.md
Merge branch 'master' of git@github.com:haricharan123/SolrNet.git
Merge branch 'master' into feature_cursormark

Conflicts:
	SolrNet/Impl/SolrQueryExecuter.cs
Added tests for CursorMarkOption