Update transifex-client requirement to latest release version 0.11b3

[nryoung]

This pins the transifex-client to 0.11b3. This allows the install of the requirements/requirements-packaging.txt on python 3.4.

Without this change the install of the devel requirements fail:

Collecting transifex-client==0.10 (from -r requirements/requirements-packaging.txt (line 8))
  Downloading transifex-client-0.10.tar.gz (68kB)
    100% |████████████████████████████████| 69kB 26.6MB/s
    Complete output from command python setup.py egg_info:
    Traceback (most recent call last):
      File "<string>", line 20, in <module>
      File "/private/var/folders/zz/zyxvpxvq6csfxvn_n32txkg4rpqcls/T/pip-build-vs8d_8zq/transifex-client/setup.py", line 14, in <module>
        if long_description.startswith(BOM):
    TypeError: startswith first arg must be str or a tuple of str, not bytes

    ----------------------------------------
    Command "python setup.py egg_info" failed with error code 1 in /private/var/folders/zz/zyxvpxvq6csfxvn_n32txkg4rpqcls/T/pip-build-vs8d_8zq/transifex-client

[xordoquy]

@nryoung thanks, this is great as 3.4 is now my default :)