Add in padUsers HTTP API call

I needed the list of users this time, so I got it. There are docs
and everything.

doc/api/http_api.md

@@ -206,6 +206,10 @@ Group pads are normal pads, but with the name schema GROUPID$PADNAME. A security
 * **padUsersCount(padID)** returns the number of user that are currently editing this pad <br><br>*Example returns:*
   * `{code: 0, message:"ok", data: {padUsersCount: 5}}`
 
+* **padUsers(padID)** returns the list of users that are currently editing this pad <br><br>*Example returns:*
+  * `{code: 0, message:"ok", data: {padUsers: [{colorId:"#c1a9d9","name":"username1","timestamp":1345228793126},{"colorId":"#d9a9cd","name":"Hmmm","timestamp":1345228796042}]}}`
+  * `{code: 0, message:"ok", data: {padUsers: []}}`
+
 * **deletePad(padID)** deletes a pad <br><br>*Example returns:*
   * `{code: 0, message:"ok", data: null}`
   * `{code: 1, message:"padID does not exist", data: null}`

src/node/db/API.js

@@ -48,6 +48,7 @@ exports.createGroupPad = groupManager.createGroupPad;
 exports.createAuthor = authorManager.createAuthor;
 exports.createAuthorIfNotExistsFor = authorManager.createAuthorIfNotExistsFor;
 exports.listPadsOfAuthor = authorManager.listPadsOfAuthor;
+exports.padUsers = padMessageHandler.padUsers;
 exports.padUsersCount = padMessageHandler.padUsersCount;
 
 /**********************/

src/node/handler/APIHandler.js

@@ -67,6 +67,7 @@ var functions = {
   "isPasswordProtected"       : ["padID"], 
   "listAuthorsOfPad"          : ["padID"],
   "padUsersCount"             : ["padID"],
+  "padUsers"                  : ["padID"],
   "sendClientsMessage"        : ["padID", "msg"]
 };
 

src/node/handler/PadMessageHandler.js

@@ -1410,3 +1410,26 @@ exports.padUsersCount = function (padID, callback) {
     callback(null, {padUsersCount: pad2sessions[padID].length});
   }
 }
+
+/**
+ * Get the list of users in a pad
+ */
+exports.padUsers = function (padID, callback) {
+  if (!pad2sessions[padID] || typeof pad2sessions[padID] != typeof []) {
+    callback(null, {padUsers: []});
+  } else {
+    var authors = [];
+    for ( var ix in sessioninfos ) {
+      if ( sessioninfos[ix].padId !== padID ) {
+        continue;
+      }
+      var aid = sessioninfos[ix].author;
+      authorManager.getAuthor( aid, function ( err, author ) {
+        authors.push( author );
+        if ( authors.length === pad2sessions[padID].length ) {
+          callback(null, {padUsers: authors});
+        }
+      } );
+    }
+  }
+}