Don't set smartindent

According to justinmk:

    Don't use smartindent, it is a legacy/deprecated feature
    replaced by 'cindent' and 'indentexpr'. Do this:

        set autoindent

    Then let the various ftplugins handle cindent and indentexpr
    on a per-filetype basis for you.

http://www.reddit.com/r/vim/comments/27j39d/can_i_write_something_that_will_automatically/ci1n6xd