Upgrade dependencies

An easy way to read few a bit of the code.

Didn't do pytz since it gave a very weird error:

```
======================================================================
FAIL: test_datetime_is_converted_to_utc (tests.core.test_timeutils.ParseTimeAsUTCTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/var/apps/backdrop/tests/core/test_timeutils.py", line 26, in test_datetime_is_converted_to_utc
    equal_to(d_tz(2012, 12, 12, 17)))
AssertionError: 
Expected: <2012-12-12 17:00:00+00:00>
     but: was <2012-12-12 16:56:00+00:00>


======================================================================
FAIL: test_with_est_date (tests.read.test_read_api_json_encoder.TestReadAPIJSONEcoder)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/var/apps/backdrop/tests/read/test_read_api_json_encoder.py", line 22, in test_with_est_date
    is_('{"date": "2014-04-29T06:00:00+00:00"}'))
AssertionError: 
Expected: '{"date": "2014-04-29T06:00:00+00:00"}'
     but: was '{"date": "2014-04-29T05:56:00+00:00"}'
```

Delving into that felt like too much trouble :trollface: