Removed the option for curators to generate a new CSV export.

As the BioCatalogue takes such a long time to generate the CSV export we have removed the option for curators to do so and instead allow curators only to download a pre-generated one.
There is now a download page that tells them when the last export was generated and how to request a new export be generated if it is not recent enough.
Moved all of the csv export logic from the curation_controller to the curation_helper so that it can be used by a rake task
Stops it from breaking if certain methods return nil
Fixed bug that would crash the generate_stats script. See comment for explanation
Rake task to generate a fresh CSV Export zip.
Fixed registry stats page

As the production stats were so large, using the cache to store the results was becoming problematic. I’ve now got the stats saved in yaml format in the data folder which can be read in by the controller when the page is opened
Updated the .gitignore to reflect the recent change to making the yaml file care about the environment
Sorted out bug where the stats page broke because some previous search queries were using utf-8.
Added installation instructions link to README.
Merge branch 'master' of github.com:myGrid/biocatalogue
Check if services' CSV export is null before calling any opertions on it. A small rewording of the text on the page as well.
Changed the stats page not to refresh ever 60 seconds and fire up a background job to generate stats.
Saves generated stats report to a new ‘reports’ subfolder in the data folder. Doesn’t bother caching reports anymore as we’re storing them in yml now
rake task to create new link checker report and save it as yaml file
Added links checker page which pulls in pre-generated yaml data and renders in a neat view
Changed the directory to be <env>_reports folder to de-clutter the data directory
Tweaked ‘no results’ error message to look a little nicer
All reports kept in their environments specific folder now so no need to gitignore them
Set max-width of stats’ search tab table so it doesn’t overspill
Changed the tabs in the stats page to use the tabs gem.