glupy: Add fops; Add/Modify structure types

Extend the following fops with Python:
  * open
  * readv
  * writev
  * opendir
  * readdir
  * readdirp
  * stat
  * fstat
  * statfs
  * setxattr
  * getxattr
  * fsetxattr
  * fgetxattr
  * removexattr
  * fremovexattr
  * link
  * unlink
  * readlink
  * symlink
  * mkdir
  * rmdir

Add fd_t, inode_t and iatt_t structure types.

Modify loc_t structure type; Alter the data types of the following
attributes - inode, parent, gfid, pargfid.

Change-Id: If0fcfb2866e21c0380a973f8ffab9ea7b6a4cd5d
Signed-off-by: Ram Raja <rraja@redhat.com>