[downloader/(common/http)] Changes calculation of the rate-limit. (Fix #2297, fix #2140, fix #595, fix #2370)
 [downloader/common] Fix possible negative sleep time in slow_down()
apply ratelimit to f4m
[common] Split _download_json
Add ability for extractor to use _parse_json
[howstuffworks] Rewrite extractor
[howstuffworks] Update extractor
Fix utils.py for PyPy on Windows

The line
```python
from __future__ import unicode_literals
```
introduced in commit [ecc0c5ee01f0e5bdd6af0c32cb5b4adcb2a2f78c](https://github.com/rg3/youtube-dl/commit/ecc0c5ee01f0e5bdd6af0c32cb5b4adcb2a2f78c) broke youtube-dl for PyPy on Windows, making it unable to locate WinAPI functions.
Error: "TypeError: function name must be a string or integer"

Adding "b" prefix to strings with WinAPI function names fixes it.
add direct screenwavemedia.com URL support
add teamfourstar.com support
release 2014.12.10
[youtube] Handle missing DASH manifest (Fixes #4421, fixes #4420)
release 2014.12.10.1
[youtube] Pass in all variables to DASH manifest (Fixes #4424)
release 2014.12.10.2
[facebook] Make thumbnail and duration optional

Fixes #4425.
Looks like both properties aren't given to us anymore. For now, just fall back to not returning them.
release 2014.12.10.3
[smotri:broadcast] Fix extraction
[zdf] Add support for channels
[youtube] Fix imports
[utils] Add "yesterday" as a date keyword