sysutils/py-tmuxp: update to 0.9.0

This release fixing compatibility with tmux 2.0.

While here, limit python version to 2.x:

"""

> Configuring for py34-tmuxp-0.9.0

Traceback (most recent call last):

File "<string>", line 1, in <module>
File "setup.py", line 25, in <module>
  readme = open('README.rst').read()
File "/usr/local/lib/python3.4/encodings/ascii.py", line 26, in decode
  return codecs.ascii_decode(input, self.errors)[0]

UnicodeDecodeError: 'ascii' codec can't decode byte 0xe4 in position 635: ordinal not in range(128)
"""

PR: 201431
Submitted by: Tony Narlock <tony@git-pull.com> (maintainer)