Updated working-draft JPMS specification and issue list

[mark.reinhold at oracle.com]

I've updated the working-draft specification and the issue list to
reflect our final meeting last week [1]:

  http://cr.openjdk.java.net/~mr/jigsaw/spec/
  http://openjdk.java.net/projects/jigsaw/spec/issues/

The specification now includes the `ModuleLayer.Controller::addExports`
method [2], and §7.7 of the draft JLS was revised to distinguish clearly
between access at compile time, access at run time, and reflective
access, in response to a comment from Volker Simonis [3].

- Mark


[1] http://openjdk.java.net/projects/jigsaw/spec/minutes/2017-05-23
[2] http://openjdk.java.net/projects/jigsaw/spec/issues/#LayerPrimitives
[3] http://mail.openjdk.java.net/pipermail/jpms-spec-comments/2017-May/000090.html