Remove M-O keybinding

It interfered with the Terminal's handling of arrow keys.

This fixes #343.
Map Option to Super and Fn to Hyper

More keybinding options is never a bad thing.
Add prefix arg to prelude-smart-open-line

With a prefix arg the command will invoke prelude-smart-open-line-above
Replace electric-indent-mode and paredit with smartparens
Ops :-)
Remove yasnippets from the list of default packages

Prelude provided just a basic config anyways. Anyone can still install
the package manually and enable it in his/her personal config.
Don't create the snippets dir
Fix some wrong keybindings
Merge pull request #349 from wzpan/readme

Fix some wrong keybindings