Fix for GitHub issue #6

It appears that the implementation of the Branch interface available
to an sBuild - and hence included in the webhook payload content - has
references to other objects that end up being circular.

From limited testing, this appears to be only evident on non-default
branches of VCS that support multiple branches in TeamCity. For example,
feature branches on GIT or HG.

To avoid these references, now pass a simple Branch bean to the content
message constructed from the implementation passed to tcWebHooks by
TeamCity.

tcwebhooks-core/src/main/java/webhook/teamcity/payload/content/WebHookPayloadContent.java

@@ -207,7 +207,7 @@ private Branch getBranch() {
 		}
 
 		public void setBranch(Branch branch) {
-			this.branch = branch;
+			this.branch = new WebHooksBranchImpl(branch);
 		}
 
 		public String getBranchName() {

tcwebhooks-core/src/main/java/webhook/teamcity/payload/content/WebHooksBranchImpl.java

@@ -0,0 +1,32 @@
+package webhook.teamcity.payload.content;
+
+import jetbrains.buildServer.serverSide.Branch;
+
+public class WebHooksBranchImpl implements Branch {
+
+	String displayName;
+	String name;
+	boolean isDefaultBranch;
+
+	public WebHooksBranchImpl(Branch branch) {
+		this.displayName = branch.getDisplayName();
+		this.name = branch.getName();
+		this.isDefaultBranch = branch.isDefaultBranch();
+	}
+
+	@Override
+	public String getDisplayName() {
+		return this.displayName;
+	}
+
+	@Override
+	public String getName() {
+		return this.name;
+	}
+
+	@Override
+	public boolean isDefaultBranch() {
+		return this.isDefaultBranch;
+	}
+
+}