Added static keyword to static classes

exercises/atbash-cipher/AtbashCipher.cs

@@ -1,6 +1,6 @@
 using System;
 
-public class Atbash
+public static class Atbash
 {
     public static string Encode(string value)
     {

exercises/atbash-cipher/Example.cs

@@ -1,7 +1,7 @@
 using System.Collections.Generic;
 using System.Linq;
 
-public class Atbash
+public static class Atbash
 {
     private const string PLAIN = "abcdefghijklmnopqrstuvwxyz";
     private const string CIPHER = "zyxwvutsrqponmlkjihgfedcba";

exercises/grains/Example.cs

@@ -1,4 +1,4 @@
-public class Grains
+public static class Grains
 {
     public static ulong Square(int n)
     {

exercises/grains/Grains.cs

@@ -1,6 +1,6 @@
 using System;
 
-public class Grains
+public static class Grains
 {
     public static ulong Square(int n)
     {

exercises/triangle/Example.cs

@@ -8,7 +8,7 @@ public enum TriangleKind
     Scalene
 }
 
-public class Triangle
+public static class Triangle
 {
     public static TriangleKind Kind(decimal side1, decimal side2, decimal side3)
     {

exercises/triangle/Triangle.cs

@@ -7,7 +7,7 @@ public enum TriangleKind
     Scalene
 }
 
-public class Triangle
+public static class Triangle
 {
     public static TriangleKind Kind(decimal side1, decimal side2, decimal side3)
     {

exercises/word-count/Example.cs

@@ -2,7 +2,7 @@
 using System.Text.RegularExpressions;
 using System.Collections.Generic;
 
-public class Phrase
+public static class Phrase
 {
     public static IDictionary<string, int> WordCount(string phrase)
     {

exercises/word-count/WordCount.cs

@@ -1,7 +1,7 @@
 using System;
 using System.Collections.Generic;
 
-public class Phrase
+public static class Phrase
 {
     public static IDictionary<string, int> WordCount(string phrase)
     {

exercises/wordy/Example.cs

@@ -2,7 +2,7 @@
 using System.Collections.Generic;
 using System.Text.RegularExpressions;
 
-public class WordProblem
+public static class WordProblem
 {
     private static readonly Regex VariableAndOperatorGroupsRegex =
         new Regex(string.Format(@"{0} {1} {0}\s*{1}*\s*{0}*", @"(-?\d+)", "(plus|minus|multiplied by|divided by)"));

exercises/wordy/Wordy.cs

@@ -1,6 +1,6 @@
 using System;
 
-public class WordProblem
+public static class WordProblem
 {
     public static int Solve(string problem)
     {