Add a RemoteName property to avoid lookups

Sometimes all you need is the name and right now there's no way of getting
it short of git_remote_lookup. While going through a lookup guarantees
that the remote exists that shouldn't be the concern of the Branch, it
should just let the caller know what's been configured as it's remote.

Author: niik

LibGit2Sharp/Branch.cs

@@ -153,6 +153,26 @@ public virtual string UpstreamBranchCanonicalName
             }
         }
 
+        /// <summary>
+        /// Get the name of the remote for the branch.
+        /// <para>
+        ///   If this is a local branch, this will return the configured
+        ///   <see cref="Remote"/> to fetch from and push to. If this is a
+        ///   remote-tracking branch, this will return the name of the remote 
+        ///   containing the tracked branch. If there no tracking information 
+        ///   this will return null.
+        /// </para>
+        /// </summary>
+        public virtual string RemoteName
+        {
+            get
+            {
+                return IsRemote
+                    ? RemoteNameFromRemoteTrackingBranch()
+                    : RemoteNameFromLocalBranch();
+            }
+        }
+
         /// <summary>
         /// Get the remote for the branch.
         /// <para>
@@ -166,16 +186,7 @@ public virtual Remote Remote
         {
             get
             {
-                string remoteName;
-
-                if (IsRemote)
-                {
-                    remoteName = RemoteNameFromRemoteTrackingBranch();
-                }
-                else
-                {
-                    remoteName = RemoteNameFromLocalBranch();
-                }
+                string remoteName = RemoteName;
 
                 if (remoteName == null)
                 {