Fixing #923 - cookie expiry is now further in the past

On a loaded server, it's possible that the cookie expiry time may
actually end up being in the future compared to the date header.  This
puts it one day in the past.  This also should be long enough to deal
with any issues regarding timezones and clocks out of sync.
Now that we have Scalariform on core, let's pretty up the skeleton files.
extracte code from md to ScalaSessionFlash.scala
Update IDE.md

I skipped to the IntelliJ section and started idea instead of having play generate .idea folder, hope this helps somebody
Merge pull request #1027 from XuefengWu/master

extract code from md to ScalaSessionFlash.scala
Merge pull request #1026 from CodeBlock/skeleton-spacing

Now that we have Scalariform on core, let's pretty up the skeleton files.
Merge pull request #1031 from q42jaap/master

Small doc change for IntelliJ IDE
Merge pull request #923 from jroper/earlier-cookie-expiry

Cookie discard may not discard the cookie for the next request