Changes File API test to write file, and improves error reporting.
Changes File API test to write file, and improves error reporting.

Enyo-DCO-1.1-Signed-off-by: Doug Reeder (reeder.29@gmail.com)

DougReeder/org.webosports.app.testr,DougReeder/org.webosports.app.testr,DougReeder/org.webosports.app.testr,DougReeder/org.webosports.app.testr