Creating Normal Files

First, we need to add new operation structs for files:

• In stamfs_iops, we add an empty stamfs_file_iops.
• In stamfs_fops, we add an empty stamfs_file_fops.
• Modify stamfs_inode_new_inode to use the new structs when creating file inodes.
• Modify stamfs_inode_read_ino in the same manner.
  Originally written by guy keren