Add upvoted route.

Upvoted route shows all stories a logged in user have upvoted
in reverse chronological order, latest upvote first.
It is not shown in the gui, but reachable at /upvoted.
Fix comment preview length bug.
Let the comment form remain when posting a top-level comment.
Add cancel button to comment editing.

This should fix issue #128.
Rename by_user to newest_by_user and sort accordingly.
Merge pull request #166 from walle/issue_165

fix ordering of newest stories by user
order newest stories by id, not created_at

same order (most likely) but id has an index on it and created_at
will need a full table scan
Merge pull request #168 from walle/issue_128

Add cancel button to comment editing.
Merge pull request #167 from walle/issue_140

fix some after-comment issues
Merge pull request #163 from walle/upvoted_fix

add /upvoted page to show a logged-in user's upvoted stories
tweak page title for /upvoted
update to rails 4.0.8 for no particular reason
typography: bigger, wider, colored code
commentbox: 15 rows instead of 5
fashion police: constrain #wrapper to 100%
Navigation: switch recent and hottest for our small community
Navigation: prominent sign-up link in footer
Gemfile: add thin
bcrypt-ruby is outdated
guess box added to home page (with /stories/guess route)