Show source language when listing

[zcbenz]

Output now becomes:

$ ./InputSourceSelector list-enabled
com.apple.keylayout.US (U.S., en)
com.sogou.inputmethod.sogou.pinyin (搜狗拼音, zh-Hans)
com.sogou.inputmethod.sogou (Sogou, en)
com.apple.inputmethod.Kotoeri.Japanese (Hiragana, ja)
com.apple.inputmethod.Kotoeri (Japanese, ja)