Translate "before-install" for Japanese.
Translate "install-by-homebrew" for Japanese.
Translate "install-by-deb" for Japanese.
Merge pull request #18 from mazgi/translate/ja/before-install

Translate "before-install" for Japanese.
Merge pull request #20 from mazgi/translate/ja/install-by-deb

Translate "install-by-deb" for Japanese.
Merge pull request #19 from mazgi/translate/ja/install-by-homebrew

Translate "install-by-homebrew" for Japanese.
plugin-development.txt: Add a second '#' to the comment line for group uncommenting of alternate serialization format option.