Adding in support for the refs command and filters in the API

src/main/java/org/kohsuke/github/GHRef.java

@@ -0,0 +1,43 @@
+package org.kohsuke.github;
+
+import java.net.URL;
+
+/**
+ * Provides information on a Git ref from GitHub.
+ *
+ * @author Michael Clarke
+ */
+public class GHRef {
+
+    private String ref, url;
+    private GHObject object;
+
+    public String getRef() {
+        return ref;
+    }
+
+    public URL getUrl() {
+        return GitHub.parseURL(url);
+    }
+
+    public GHObject getObject() {
+        return object;
+    }
+
+
+    public static class GHObject {
+         private String type, sha, url;
+
+        public String getType() {
+            return type;
+        }
+
+        public String getSha() {
+            return sha;
+        }
+
+        public URL getUrl() {
+            return GitHub.parseURL(url);
+        }
+    }
+}

src/main/java/org/kohsuke/github/GHRepository.java

@@ -406,6 +406,25 @@ public GHCompare getCompare(String id1, String id2) throws IOException {
         return compare.wrap(this);
     }
 
+    /**
+     * Retrieves all refs for the github repository.
+     * @return an array of GHRef elements coresponding with the refs in the remote repository.
+     * @throws IOException on failure communicating with GitHub
+     */
+    public GHRef[] getRefs() throws IOException {
+       return root.retrieve().to(String.format("/repos/%s/%s/git/refs", owner.login, name), GHRef[].class);
+    }
+
+    /**
+     * Retrienved all refs of the given type for the current GitHub repository.
+     * @param refType the type of reg to search for e.g. <tt>tags</tt> or <tt>commits</tt>
+     * @return an array of all refs matching the request type
+     * @throws IOException on failure communicating with GitHub, potentially due to an invalid ref type being requested
+     */
+    public GHRef[] getRefs(String refType) throws IOException {
+        return root.retrieve().to(String.format("/repos/%s/%s/git/refs/%s", owner.login, name, refType), GHRef[].class);
+    }
+
     /**
      * Gets a commit object in this repository.
      */