Add prefix arg support prelude-update-packages

With a prefix arg it will update all installed packages.
Merge branch 'master' of github.com:bbatsov/prelude
Fix epl-upgrade invocation
[Fix #433] Disable problematic binding M-[
Simplify sexp wrapping code
Add wrapping commands to ielm-map
Improve tab's behavior

It now does both indentation and completion (when supported)
Add browse-kill-ring package
Adds comments to sample modules.
Updates key chord bindings.
Merge pull request #457 from climatewarrior/updateKeyChords

Updates key chord bindings.
Merge pull request #456 from climatewarrior/add-module-docs

Adds comments to sample modules.
Enable browse-kill-ring's default keybindings
Improve prelude-eval-and-replace
Don't use C-x SPC as it's used in Emacs 24.4 by default for rectangular selection
Change C-c SPC to C-c j to avoid a conflict in org-mode

In org-mode C-c SPC is bound to `org-table-blank-field`
Bind ace-jump-mode to s-. as well
Mention guru-warn-only
Update prelude-lisp.el

Use `completion-at-point` since `lisp-complete-symbol` is obsolete as of Emacs 24.4.
Merge pull request #465 from bixuanzju/patch-1

`lisp-complete-symbol` is obsolete