Add Multiple Delete on Captures

[dataprop]

Hi,
This pull request adds the functionality to perform multiple delete on the Admin/Capture page.
Relates to the issue https://github.com/jekhokie/raspberry-noaa-v2/issues/447

This is done by adding a checkbox next to each capture. When one or more captures are selected, a button is visible at the bottom of the page, which when clicked provides a summary dialog of the captures to be deleted. From that model box, the user can confirm the deletion and the system will delete the selected captures.

Additionally, in the table with the passes, the header for the checkbox has an option to toggle the selected checkboxes, allowing for ease of selecting all captures and then un checking the ones which should not be deleted.

I have made changes to the en.php, for some text which is shown in the screens, but I do not have the ability to translate into the other languages, so this would need to be done by someone who is familiar with those languages.

Apologies, but my editor seems to have formatted some of the files in a different style than the original.

I have followed the style as used for single delete.

Let me know if you have any questions.