Add .gitconfig, with aliases and pager config

The pager config colors the diff and use less as a pager,
After having called "git diff", you just will just have to type 'n'
to iterate over diff sections.

.gitconfig

@@ -0,0 +1,20 @@
+[user]
+    name = nojhan
+    email = nojhan@nojhan.net
+[alias]
+    up = pull origin
+    st = status
+    di = diff
+    co = checkout
+    # create branch
+    cb = checkout -b
+    ci = commit
+    br = branch
+    sta = stash
+[core]
+    # color the diff, use less as pager
+    # -R is necessary to display colors in less
+    # the '+' calls a command at start, that will jump to the first diff section
+    # then, you just have to type 'n' to iterate over diff sections
+    pager = colordiff | less -R +'/-{3}'
+