add functionality to PSVersionTable to include GitCommitID and update tests

src/Microsoft.PowerShell.ConsoleHost/project.json

@@ -18,7 +18,8 @@
     "content": [
         "Modules",
         "../Modules",
-        "powershell.exe"
+        "powershell.exe",
+        "../../.version"
     ],
 
     "frameworks": {

src/System.Management.Automation/engine/PSVersionInfo.cs

@@ -63,6 +63,7 @@ namespace System.Management.Automation
             _psVersionTable["PSEdition"] = PSEditionValue;
             _psVersionTable["CLRVersion"] = Environment.Version;
             _psVersionTable["BuildVersion"] = GetBuildVersion();
+            _psVersionTable["GitCommitId"] = GetCommitInfo();
             _psVersionTable["PSCompatibleVersions"] = new Version[] { _psV1Version, _psV2Version, _psV3Version, _psV4Version, _psV5Version, _psV51Version };
             _psVersionTable[PSVersionInfo.SerializationVersionName] = new Version(InternalSerializer.DefaultVersion);
             _psVersionTable[PSVersionInfo.PSRemotingProtocolVersionName] = RemotingConstants.ProtocolVersion;
@@ -81,6 +82,18 @@ namespace System.Management.Automation
             return new Version(buildVersion);
         }
 
+        // Get the commit id from the .version file. If the .version file doesn't exist, use the string "N/A"
+        static internal string GetCommitInfo()
+        {
+            try {
+                string assemblyPath = IO.Path.GetDirectoryName(typeof(PSVersionInfo).GetTypeInfo().Assembly.Location);
+                return (IO.File.ReadAllLines(IO.Path.Combine(assemblyPath,".version"))[0]);
+            }
+            catch (Exception e){
+                return e.Message;
+            }
+        }
+
         #region Private helper methods
 
         // Gets the current WSMan stack version from the registry.