RFR: JDK-8235667: IOUtils.copyFile() problems.

[Andy Herrick]

Please review the jpackage fix at [1] to issue [2].

This is a change to jpackage/internal/IOUtils.copyFile() to essentially 
replace it's content with a call to Files.copy()

[1] http://cr.openjdk.java.net/~herrick/8235667/webrev.01/

[2] https://bugs.openjdk.java.net/browse/JDK-8235667

/Andy