front.py: import markdown from the right file
front.py: import markdown from the right file

Per 0962e34e8 (Move everything into filters) markdown funciton is moved to new
location.

Signed-off-by: Wei Liu <079fafa87fda223ee1bc02c2e01be5a73f34e147@liuw.name>

w15971597/june,Ricardo666666/june,beni55/june,w15971597/june,fanne/june,Denniskevin/june,yuewolf/june,fanne/june,pythoncn/june,jubel-han/june,xingkaixin/june,yuewolf/june,jubel-han/june,beni55/june,yuewolf/june,Denniskevin/june,Denniskevin/june,Ricardo666666/june,beni55/june,xingkaixin/june,xingkaixin/june,Ricardo666666/june,w15971597/june,jubel-han/june,pythoncn/june,fanne/june