Merge HF 1.7 with HF 1.7-JP to provide single localized extension, which will select language based on browser settings for UI.

I perform merge of HF 1.7 and HF 1.7-JP branches. Could somebody from Japanese reading guys verify that my changes shows Japanese UI correctly for this version?

Hi, We've checked builds from both HF 1.6 & 1.7 merged branches. Japanese UIs are shown correctly and switching between ja-JP and en-US by changing firefox's language works well. Everything is fine. This will be good for localizing HF into other languages and maintenance.