Added Get User List methods to win_client and linux_client

* Added get_user_list method to windows_client which uses the winrm
  remote client to run a powershell command to get user objects,
  parse them into dictionaries and make a list of the usernames
  on the target instance
* Added get_user_list method to linux_client which reads the
  /etc/passwd file on the target instance and returns a list of
  the usernames.

Change-Id: Ifeb408929d598fdff82a7f4f8c0f0912ff8fd1f4

cloudcafe/compute/common/clients/remote_instance/linux/linux_client.py

@@ -149,6 +149,19 @@ class LinuxClient(RemoteInstanceClient):
             uptime = float(result.stdout.split(' ')[0])
             return uptime
 
+    def get_local_users(self):
+        """
+        Get a list of the local user accounts on the server
+
+        @return: A list of users
+        @rtype: List of strings
+        """
+
+        command = 'cat /etc/passwd | cut -d: -f1'
+        output = self.ssh_client.execute_command(command)
+        if output:
+            return output.stdout.split()
+
     def create_file(self, file_name, file_content, file_path=None):
         """
         Creates a new file with the provided content.

cloudcafe/compute/common/clients/remote_instance/windows/windows_client.py

@@ -146,6 +146,26 @@ class WindowsClient(RemoteInstanceClient):
         diff = now - last_boot
         return diff.total_seconds()
 
+    def get_local_users(self):
+        """
+        Get a list of the local user accounts on the server
+
+        @return: A list of users
+        @rtype: List of strings
+        """
+
+        command = ('powershell gwmi Win32_UserAccount')
+        output = self.client.execute_command(command)
+        if not output:
+            return None
+        raw_output = output.std_out.split('\r\n\r\n')
+        raw_users = [user for user in raw_output if user]
+        user_list = []
+        for user in raw_users:
+            user_info = self._convert_powershell_list_to_dict(user)
+            user_list.append(user_info.get('Name'))
+        return user_list
+
     def create_file(self, file_name, file_content, file_path):
         """
         Creates a new file with the provided content.