add new packages, modify keybindings

init.el: add slime, ace-jump-mode, powerline, and flycheck-pos-tip to
packages-list
keybindings.el: add keybinding for ace-jump-mode
keybindings.el: add more sensible keybindings for backward-paragraph and
forward-paragraph setup-flycheck.el: activate flycheck-pos-tip
setup-python.el: add autocomplete for python
setup-themes.el: move theme settings to it's own file. add cycling function