Corrected addition ReSharper Code Inspections

After correcting the first ReSharper Code Inspection issue for the BuildServer Class, there were a number of additional code inspections errors created.  This commit aims to correct these.

Author: gep13

AcceptanceTests/ExecCmdLineArgumentTest.cs

@@ -21,7 +21,7 @@ public void RunExecViaCommandLine()
 
                 var buildFile = Path.Combine(fixture.RepositoryPath, "RunExecViaCommandLine.proj");
                 File.Delete(buildFile);
-                var buildFileContent = @"<?xml version=""1.0"" encoding=""utf-8""?>
+                const string buildFileContent = @"<?xml version=""1.0"" encoding=""utf-8""?>
 <Project xmlns=""http://schemas.microsoft.com/developer/msbuild/2003"">
   <Target Name=""OutputResults"">
     <Message Text=""GitVersion_FullSemVer: $(GitVersion_FullSemVer)""/>

AcceptanceTests/MsBuildProjectArgTest.cs

@@ -18,7 +18,7 @@ public void RunsMsBuildProvideViaCommandLineArg()
 
                 var buildFile = Path.Combine(fixture.RepositoryPath, "RunsMsBuildProvideViaCommandLineArg.proj");
                 File.Delete(buildFile);
-                var buildFileContent = @"<?xml version=""1.0"" encoding=""utf-8""?>
+                const string buildFileContent = @"<?xml version=""1.0"" encoding=""utf-8""?>
 <Project xmlns=""http://schemas.microsoft.com/developer/msbuild/2003"">
   <Target Name=""OutputResults"">
     <Message Text=""GitVersion_FullSemVer: $(GitVersion_FullSemVer)""/>

GitVersionCore/BuildServers/GitHelper.cs

@@ -7,6 +7,8 @@ namespace GitVersion
 
     public static class GitHelper
     {
+        private const string MergeMessageRegexPattern = "refs/heads/pull(-requests)?/(?<issuenumber>[0-9]*)/merge(-clean)?";
+
         public static void NormalizeGitDirectory(string gitDirectory, Authentication authentication, string branch = null)
         {
             using (var repo = new Repository(gitDirectory))
@@ -51,30 +53,20 @@ public static bool LooksLikeAValidPullRequestNumber(string issueNumber)
             }
 
             uint res;
-            if (!uint.TryParse(issueNumber, out res))
-            {
-                return false;
-            }
-
-            return true;
+            return uint.TryParse(issueNumber, out res);
         }
 
         public static string ExtractIssueNumber(string mergeMessage)
         {
             // Github Message: refs/heads/pull/5/merge
             // Stash Message:  refs/heads/pull-requests/5/merge-clean
 
-            string pattern = "refs/heads/pull(-requests)?/(?<issuenumber>[0-9]*)/merge(-clean)?";
-
-            var regex = new Regex(pattern);
+            var regex = new Regex(MergeMessageRegexPattern);
             var match = regex.Match(mergeMessage);
 
             string issueNumber = null;
 
-            if (match != null)
-            {
-                issueNumber = match.Groups["issuenumber"].Value;
-            }
+            issueNumber = match.Groups["issuenumber"].Value;
 
             return issueNumber;
         }

GitVersionExe/HelpWriter.cs

@@ -6,8 +6,7 @@ class HelpWriter
     {
         public static void Write()
         {
-            var message =
-@"Use convention to derive a SemVer product version from a GitFlow or GitHub based repository.
+            const string message = @"Use convention to derive a SemVer product version from a GitFlow or GitHub based repository.
 
 GitVersion [path] [/l logFilePath]