Add markdown blob support
Add embed data URI image blob support
utils: Make the embedded image code use mimetypes

This patch makes minor changes to the code that handles embedded images,
mostly to make it use mimetypes, and to remove SVG support (at least for now)
due to security concerns.

Signed-off-by: Alberto Bertogli <albertito@blitiri.com.ar>
Make embedding markdown and images configurable per-repo

This patch introduces the embed_markdown and embed_images configuration
options, so users can enable and disable those features on a per-repository
basis.

Signed-off-by: Alberto Bertogli <albertito@blitiri.com.ar>
Use the status_code attribute to tell 404s appart

Newer versions of bottle have a string in the e.status attribute, and the
status code can be found in e.status_code, which should be backwards
compatible.

Signed-off-by: Alberto Bertogli <albertito@blitiri.com.ar>