Warning output when spacemacs loads epresent

[Plancalkuele]

Hi there,
I loaded the epresent.el package within spacemacs by defining the following in ~/.spacemacs:
dotspacemacs-additional-packages '(epresent)

and I get the following warnings:

epresent.el:48:1:Warning: defface for `epresent-title-face' fails to specify
    containing group
epresent.el:51:1:Warning: defface for `epresent-heading-face' fails to specify
    containing group
epresent.el:54:1:Warning: defface for `epresent-subheading-face' fails to
    specify containing group
epresent.el:57:1:Warning: defface for `epresent-author-face' fails to specify
    containing group
epresent.el:60:1:Warning: defface for `epresent-bullet-face' fails to specify
    containing group
epresent.el:63:1:Warning: defface for `epresent-hidden-face' fails to specify
    containing group
epresent.el:94:1:Warning: `make-variable-frame-local' is an obsolete function
    (as of 22.2); explicitly check for a frame-parameter instead.

In epresent-mode:
epresent.el:454:9:Warning: assignment to free variable
    `org-hide-pretty-entities'

[sellout]

PR #41 addresses most of these (all the ones that say “fails to specify containing group”).

The others look easy to fix as well.