Update ideas page layout and sidebar

@jkridner I have updated the ideas page to look best on all screens with some additional tweaks to make the page look clearer overall.

• On the ideas page, we have a link for the forum GSoC page

• On all other pages, we have a forum link that allows users to create a new post with GSoC as a description and tag,

• This is what we see after clicking that button

• The PDF download button is now following the theme look and feel,