Fixed error when edX subtitles were not available.
Merge remote-tracking branch 'origin/master'
Fix issue #48

Additionally I made slight visual changes for coherence, and I renamed
the temp variable as suggested.
Fix error when downloading edx subtitles with python 3

To test it happened with the CS1156x week 3 first video
Merge branch 'master' of https://github.com/iemejia/edx-downloader into iemejia-master

Conflicts:
	edx-dl.py
Merge branch 'master' of github.com:shk3/edx-downloader