added credential helper

.gitconfig

[user]
        name = foo bar
        email = foo@bar.com
[color]
        ui = auto
[push]
        default = tracking
[http]
        sslVerify = False
[alias]
        co = checkout
        ci = commit
        st = status
        br = branch
        d = diff
        dc = diff --cached
        di = diff
        dic = diff --cached
[credential]
        helper = "cache --timeout=3600"