client.shared: Remove pexpect module and update code to use aexpect module.

This modifies big parts of Autotest to remove previous dependence on pexpect
and then making use of virttest's aexpect module.

So basically we are:

* Removing pexpect.py and pxssh.py modules.
* Importing modules aexpect.py, data_dir.py, rss_client.py and remote.py
  from virttest.
* Importing selected functions from virttest's utils_misc.py into utils.py.
* Updating/removing references from pexpect to aexpect.
* Make ssh_key module to use aexpect and remote.
  - Also: function setup_ssh_key(): default port is 22.

Signed-off-by: Ruda Moura <rmoura@redhat.com>
Merge pull request #810 from ruda/use_aexpect

client.shared: Remove pexpect module and update code to use aexpect module
client.shared.utils: add get_unique_name() function

This function is usefull whenever we want to get unique name and
we have a function to verify it's unique.

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
Merge pull request #811 from ldoktor/framework

client.shared.utils: add get_unique_name() function
client.shared.remote: Fix SSH's options passing syntax.
See PR #1560.

Signed-off-by: Ruda Moura <rmoura@redhat.com>
Merge pull request #814 from ruda/remote_option_syntax

client.shared.remote: Fix SSH's options passing syntax.