Homepage news items section rework

[luistoptal]

Pull request for issue: #208

This is a pull request for the following functionalities:

• full rework of news section in home page

How to test?

Visit the home page and verify the following:

• I expect there are no news items to display, so the section should not be displayed at all
• go to protected/components/NewsAndFeedsService.php and in the getTodaysNews function remove the second conditional so that all news are displayed
• refresh the home page. you should see a news section with a carousel and news boxes
• clicking on a "read more" link should open the detail page

alternatively you can create more news items from the admin page http://gigadb.gigasciencejournal.com/news/admin and they should show up in the home page

How have functionalities been implemented?

• the carousel uses the bootstrap carousel and overrides the styles to match the gigadb colors and to make it look better
• the logic was tweaked to cover a handful of use cases:
  • the carousel is responsive and reactive to the screen width
  • mobile shows one item
  • medium screen shows two items
  • desktop shows three items
  • if the number of items to display is less than the maximum, for example, for desktop, if there are just two news items, rather than showing a blank space, the two news items fill all the space
  • if there are less news items than the maximum that can be displayed at any given time (e.g. 3 for desktop) then the carousel controls are hidden

Any issues with implementation?

--

Any changes to automated tests?

tests pass. As far as I have seen, there are no acceptance tests covering this case