Set key bindings for `next-hunk` and `previous-hunk` functions of
git-gutter-mode.
Indent argument lists sensibly in java-mode.

"Sensibly" currently means adding four spaces to indentation of current
line (i.e., increase nesting level by one) when moving argument lists to
next line.

Sources:

- http://stackoverflow.com/questions/6952369/java-mode-argument-indenting-in-emacs
- http://www.emacswiki.org/emacs/IndentingC