Fixing broken image links in old wikidocs

The wikidocs for version 0.3.1 and earlier used absolute image links
into titan's master tree on Github that have changed since the old
wikidocs were generated, breaking the images.  I made new folders for
the affected versions in the pattern wikidoc/$VERSION/images/ and
copied the images into the new folders.  These file copies don't
actually increase the size of the repo, since all the necessary files
already existed in wikidoc/0.3.2/images/.  Git just makes new links to
the previously-stored blob objects.

To make the old html point to these new wikidoc/$VERSION/images/
files, I ran the following replacements on wikidoc html in versions
[0.1.0, 0.3.1]:

for h in *.html; do
  sed -ri \
    's|https://github.com/thinkaurelius/titan/raw/master/doc/images/|images/|g;
     s|https://raw.github.com/thinkaurelius/titan/master/doc/images/|images/|g' \
    $h;
done

The JS and CSS seem to be OK.