modify colors of status for tmux
improve install-settings and .gitconfig

* remove push.default from .gitconfig: push.default 'simple' value was
  added in 1.7.11 version

* add git aliases for git diff command

* set push.default in install-settings script to check git version
improve sources for elit

* improve readability of sources for elit

* fix a problem: instead of git@github.com:xxxx, use the following
  scheme for github.com

  git://github.com/xxxx