Subtitle encoding

[kktuax]

As omxplayer needs UTF-8 encoding

Integrate with periscope? https://github.com/patrickdessalle/periscope/issues/7

Package for charset detection:

• https://pypi.python.org/pypi/chardet
• https://pypi.python.org/pypi/cchardet/0.3.5
• Magic: http://stackoverflow.com/a/16203777

Using External command: http://stackoverflow.com/a/9200975