Do not send email to comment author

Noosfero sends an email to all admins of a commnunity when a new
comment is posted. This commit removes the author of the comment from
the recipient list.

Additionally, the comment notifier tests were rewritten. The way it was
implemented, the author of the article was always the same as the author
of the comment. Now, these authors are different.
Adds default notice to disabled enterprise
Review INSTALL file
ignore cache files in general
Not needed to import colorbox.css explicitly

Noosfero already includes that. Besides, that URL was broken anyway.
Extract Method to encapsulate access to the cart
creating author_id method in article class to return the author id when the author exists
new users should create person with name equals to user name not user login
Checkpoint: validated the idea of keeping the cart in an indepent cookie

There are a couple of FIXME's there, plus the whole thing has to be
refactored:

  * the shopping cart controller must be moved out of the profile
    namespace, because we can't know to which profile we should make the
    AJAX request to load the cart

  * there are too many unecessary AJAX requests.

  * most of the cart functionality must probably be encapsulate into
  * proper objects.
Moving controller out of the profile scope
Finish move to global scope; most tests broken
Move JS code out of HTML template
Testing article approval with an article that has a nil author
Finish moving everything to /plugins/shopping_cart
Make sure well-behaved plugin cookies always pass through
Remove embarassing debug print
Fix unit tests
Finish fixing the tests.

Fixing the functional tests was easier than I though it would. :)
Remove catch-all rescue clause

It was masking a programming error, which is now fixed.
Fix cart cleaning with path-specific cookie