Add undo-tree to the default Prelude packages
Merge branch 'master' of github.com:bbatsov/prelude

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Fix #264 - disable autoindent on yank for python-mode
Load list of prelude modules.
Merge remote-tracking branch 'upstream/master'

* upstream/master:
  Fix #264 - disable autoindent on yank for python-mode
  Add undo-tree to the default Prelude packages