Error for globus transfer failure

[kylechard]

At the moment if the transfer fails we get a FileNotFoundError. Ideally, we should tell the user that the transfer failed and perhaps relay the Globus error message.

[annawoodard]

We think this is because Kyle was not calling .result()

[annawoodard]

(deferring this because it relies on #169 and is a substantial enough change it will not be ready for 0.5)

[lukaszlacinski]

Parsl 0.5.0 implements explicit staging, so it requires calling result() on a DataFuture object.