Make coverage plugin compatible with py-coverage 4.2

--- nose/plugins/cover.py.orig	Sun Oct  2 20:23:01 2016
+++ nose/plugins/cover.py	Sun Oct  2 20:22:32 2016
@@ -187,7 +187,7 @@ class Coverage(Plugin):
                     for name, module in sys.modules.items()
                     if self.wantModuleCoverage(name, module)]
         log.debug("Coverage report will cover modules: %s", modules)
-        self.coverInstance.report(modules, file=stream)
+        self.coverInstance.report(modules, file=stream, show_missing=True)
 
         import coverage
         if self.coverHtmlDir:
@@ -207,7 +207,7 @@ class Coverage(Plugin):
         # make sure we have minimum required coverage
         if self.coverMinPercentage:
             f = StringIO.StringIO()
-            self.coverInstance.report(modules, file=f)
+            self.coverInstance.report(modules, file=f, show_missing=True)
 
             multiPackageRe = (r'-------\s\w+\s+\d+\s+\d+(?:\s+\d+\s+\d+)?'
                               r'\s+(\d+)%\s+\d*\s{0,1}$')