Display map samples tab in dataset page

[luistoptal]

Pull request for issue: #718

• Added new tab to the dataset page "Samples Map" which is displayed only if the dataset has "locations"
  http://gigadb.gigasciencejournal.com/dataset/100020
  
• Refactored the code related to the map to make it more reusable and maintainable
• Updated map popup styles

How to test?

• Navigate to http://gigadb.gigasciencejournal.com/dataset/100020 and check that the Samples Map tab exists and displays a map
• Optionally, for a more complete view in protected/views/shared/_mapbrowse.php set the USE_TEST_LOCATIONS to true and refresh the map. I have left this test for reviewers to have an easy time seeing a more complete map, but I think it would be ok to remove it after this is reviewed
• Note that you can now click outside the popup to close it

How have functionalities been implemented?

• Abstracted the map widget to a reusable partial protected/views/shared/_mapbrowse.php and most of the code was refactored to protected/js/map-browse/index.js so that we can reuse the map in multiple views
• The code in the SiteController that was in charge of building the locations array for the map is moved to a helper component protected/components/SampleLocationHelper.php so that it can be reused in the DatasetController
• Cleaned up styles in less/modules/map.less mainly to make the popup look better
• All the code refactored does the same as before, I just cleaned it up a bit and made html selector access more maintainable

Any issues with implementation?

• I added a generateRandomLocation function that adds mock locations for testing. I would prefer to simply have more test data in local dev
• The samples map is not accessible because the popups are not keyboard accessible. As far as I know there is no simple way around that provided by OpenLayers. I believe a UI which provides an alternative to the map would be a good idea. It depends on the goal of the map. If the goal is to let the user know samples by region then we could display a list of samples grouped by region and provide the links to the datasets
• the popup links looks like this http://dx.doi.org/10.5524/${dataset} but link / redirect to the production gigadb website (from the local dev site). It looks like we redirect in the controller. It is not a big problem but for consistency I think it might be better to redirect to the current domain
• I expect YII_DEBUG to be true in test environments and false in production but it would be good to confirm. I would like to use an environment variable that is only true on local dev

Any changes to automated tests?

• I added a test to check for the presence of the map tab
• As of now I cannot run acceptance tests, I run into

Db: SQLSTATE[08006] [7] invalid integer value "%GIGADB_PORT%" for connection option "port" while creating PDO connection