metadata-extractor: extractor metadata modal

[xiaom]

There are some unresolved UI problems.

1. Disable the apply button before the extraction is completed. ng-disabled does not work as I expected.
2. Close the modal when I apply the changes. I use ng-click="applyMetadata();$hide()" in the code. But it seems $hide() is not executed.

[krzysztof]

I've pushed some minor fixes. Overall looks nice.

I encountered this error: inveniosoftware/invenio-files-processor#7
I can send you the file which causes this later.

1. fixed - I am disabling each individual button.
2. fixed - I don't close the modal at all since now there's multiple buttons. the user is supposed to close it with a "Close" button. But strangely - even before the changes the modal was closing for me ...