Fix file upload bug in DelegatePaperView

[srisainachuri]

For some files, especially larger ones, uploading position papers will error and not successfully upload. Most likely cause of issue is history.redirect refreshes the page before the upload actually finishes.

Code pointers:
DelegatePaperView.js

[erwang01]

We can consider moving history.redirect to inside the upload callback function.

huxley/huxley/www/js/components/DelegatePaperView.js

Lines 220 to 222 in da7a189

	_handleSuccess = (response) => {
	window.alert("Your paper has been successfully uploaded!");
	};

This way we only redirect upon success. However #785 is probably a better way of doing things.

[srisainachuri]

Moving the history.redirect works! #785 is probably cleaner, currently looking into why the existing listener doesn't suffice.

[erwang01]

_handleSuccess doesn't seem to change the state at all. Try moving this into _handleSuccess?

huxley/huxley/www/js/components/DelegatePaperView.js

Lines 212 to 214 in da7a189

	this.setState({
	uploadedFile: null,
	});

I'm not entirely sure what the purpose of resetting this state is but I guess it lets the user upload a new file if they want to change it?

Also what does a listener do again?