Update link to FOSDEM CFP

Let's link to the local FOSDEM CFP page:  it provides much better detail
Extend the community room CFPs

Let's leave the community proposals open as long as the main room proposals.  This will also allow more time for proposals
Update CFP to 1 Dec

Moves the community CFP to the same as the devroom CFP deadline:  1 Dec
Merge pull request #10 from nathenharvey/extend-deadline

Extend deadline for community rooms