define function 'ci' for git commit

see http://qiita.com/ken_c_lo/items/f4a156ee492bf19dc9b3
rm bin/git-ci
Revert "rm bin/git-ci"

This reverts commit ada0f71f4060a84ccb2ba668bdf8e4ac2684bd43.
Revert "define function 'ci' for git commit"

This reverts commit 3a6f8384280d9727cde9307ac08338af0dba8584.