radio.json location

[csonuryilmaz]

When main.rb is called from other system folders (cwd != project root) radios.json file couldn't be read.

List of Radio Stations
----------------------
github/radiobox/main.rb:71:in `read': No such file or directory @ rb_sysopen - radios.json (Errno::ENOENT)
	from github/radiobox/main.rb:71:in `select_radio_station'
	from github/radiobox/main.rb:90:in `show_options'
	from github/radiobox/main.rb:100:in `show_options'
	from github/radiobox/main.rb:104:in `<main>'