hb-install-bootconfig: update translation
Tiny fix: en to ja

As noted at https://twitter.com/okano_t/status/473226089154609152 chnage en to ja.
hb-install-bootconfig: reviewed. LGTM. issue #13
hb-install-bootconfig: Commit to CVS #13
Merge pull request #13 from gentoojp/hb-install-bootconfig

hb-install-bootconfig: update translation