emacs:move custom.el to end

move custom.el to end to avoid any unnecessary setting overwrite.

Signed-off-by: Ratheesh S <ratheeshreddy@gmail.com>
emacs: Add some improvements

- Add git gutter fringe for X version
MELPA version is currently used due to fringe-helper version issue.
This should be eventually removed once that is fixed.
- Fix redo key binding to undo-tree-redo.
- Add default font config
currently only linux is tested(Inconsolata!). Need to test on my
Mac and if required on windows.

Signed-off-by: Ratheesh S <ratheeshreddy@gmail.com>