pip: Update to version 1.5.4.

Signed-off-by: Rudá Moura <ruda.moura@gmail.com>
Rename pip to python-pip.

Signed-off-by: Rudá Moura <ruda.moura@gmail.com>
Adopt python-mock.

Signed-off-by: Rudá Moura <ruda.moura@gmail.com>
Rename virtualenv to python-virtualenv.

Update to version 1.11.4.

Signed-off-by: Rudá Moura <ruda.moura@gmail.com>