Add a progress bar for the importing CSV files page

[ZeroCool940711]

When using the CSV page (http://domain:port/search-apps/csv/create) a progress bar would be useful, sometimes it's hard to tell whether your CSV file is been uploaded or its just finished uploading and is processing or if its stuck. Its most likely just uploading and its working but it's hard to tell, Ive found myself cancelling the upload by refreshing the page because I've though its stuck or it's a problem with my internet.