Add custom presets folder option
Changing option from presets to preset
Merge remote-tracking branch 'upstream/master'

Conflicts:
	lib/fluent-ffmpeg.js
	test/args.test.js
Fix documentation
Merge remote-tracking branch 'upstream/master'

Conflicts:
	README.md
	lib/fluent-ffmpeg.js
Merge pull request #208 from kusmayadi/master

Add custom presets folder option