8199912: jshell tool: /open from URI

[Robert Field]

Please review the following, contributed by:

           Michal Vala

Thank you Christian Stein for your comments.


Bug:

     https://bugs.openjdk.java.net/browse/JDK-8199912

Webrev:

     http://cr.openjdk.java.net/~rfield/8199912v1.webrev/


-Robert