Added support for entries without a published date.

Previously the view crashed when trying to display the publish date for these.

Also the log directory will be commited to github, but any *.log files inside will be ignored.
Changed log4r configuration so that it doesn't output to stdout in the development environment.

It was unnecessary because if we run a "rails server" command, output is printed to the shell as well as to the file. The old log4r configuration caused every log line to be written twice to the shell.
Entries are sorted in the view in descending order, first by the published column, then by the created_at column.

This ensures that in those cases in which a feed has no published date for its entries, at least they are order by the date in which they were saved in the Feedbunch database (which should match the order in which those entries were originally published, if all entries are from the same feed).
Corrected a couple of view comments.
Order folders in the sidebar by alphabetical title order.