MLT query: add support for minimum_should_match

Closes #1354

Author: gmarz

src/Nest/DSL/Query/MoreLikeThisQueryDescriptor.cs

@@ -21,6 +21,9 @@ public interface IMoreLikeThisQuery : IQuery
 		[JsonProperty(PropertyName = "percent_terms_to_match")]
 		double? TermMatchPercentage { get; set; }
 
+		[JsonProperty(PropertyName = "minimum_should_match")]
+		string MinimumShouldMatch { get; set; }
+
 		[JsonProperty(PropertyName = "stop_words")]
 		IEnumerable<string> StopWords { get; set; }
 
@@ -84,6 +87,7 @@ protected override void WrapInContainer(IQueryContainer container)
 		public IEnumerable<PropertyPathMarker> Fields { get; set; }
 		public string LikeText { get; set; }
 		public double? TermMatchPercentage { get; set; }
+		public string MinimumShouldMatch { get; set; }
 		public IEnumerable<string> StopWords { get; set; }
 		public int? MinTermFrequency { get; set; }
 		public int? MaxQueryTerms { get; set; }
@@ -108,7 +112,9 @@ public class MoreLikeThisQueryDescriptor<T> : IMoreLikeThisQuery where T : class
 		string IMoreLikeThisQuery.LikeText { get; set; }
 
 		double? IMoreLikeThisQuery.TermMatchPercentage { get; set; }
-	
+
+		string IMoreLikeThisQuery.MinimumShouldMatch { get; set; }
+		
 		IEnumerable<string> IMoreLikeThisQuery.StopWords { get; set; }
 
 		int? IMoreLikeThisQuery.MinTermFrequency { get; set; }
@@ -212,6 +218,19 @@ public MoreLikeThisQueryDescriptor<T> TermMatchPercentage(double termMatchPercen
 			this.Self.TermMatchPercentage = termMatchPercentage;
 			return this;
 		}
+
+		public MoreLikeThisQueryDescriptor<T> MinimumShouldMatch(string minMatch)
+		{
+			this.Self.MinimumShouldMatch = minMatch;
+			return this;
+		}
+
+		public MoreLikeThisQueryDescriptor<T> MinimumShouldMatch(int minMatch)
+		{
+			this.Self.MinimumShouldMatch = minMatch.ToString();
+			return this;
+		}
+
 		public MoreLikeThisQueryDescriptor<T> Boost(double boost)
 		{
 			this.Self.Boost = boost;

src/Tests/Nest.Tests.Unit/Search/Query/Singles/MoreLikeThisQueryJson.cs

@@ -161,6 +161,7 @@ public void TestMoreLikeThisAllQuery()
 						.StopWords(new[] { "thou", "shall" })
 						.BoostTerms(1.4)
 						.TermMatchPercentage(12)
+						.MinimumShouldMatch("30%")
 						.Boost(1.1)
 						.Analyzer("my_analyzer")
 					)
@@ -171,6 +172,7 @@ public void TestMoreLikeThisAllQuery()
 				fields : [""name"" ],
 				like_text : ""elasticsearcc"",
 				percent_terms_to_match: 12.0,
+                minimum_should_match: ""30%"",
 				stop_words: [
 					""thou"",
 					""shall""