Add support for PepperFlash plugin

The NPAPI flash version is stuck at 11.2 so it's better to support newer PepperFlash.

There are two options for doing this:
1. Implementing native support for PepperFlash(libpepflashplugin.so)
2. Implementing support for freshplayer plugin(which is an NPAPI wrapper for libpepflashplugin.so)

For more info look at:
http://www.webupd8.org/2012/09/how-to-make-chromium-use-flash-player.html
http://www.webupd8.org/2015/01/fresh-player-plugin-sees-new-release.html
https://github.com/i-rinat/freshplayerplugin