Bug 1374827 - Remove lines dealing with em:unpack from mozscreenshots extension. r=mconley

MozReview-Commit-ID: 7kSOhkx6idu

--HG--
extra : rebase_source : 44affd0b847b01409bef3625fcf5b72815f442d0

browser/tools/mozscreenshots/mozscreenshots/extension/install.rdf

@@ -12,9 +12,6 @@
 #expand <em:version>__MOZILLA_VERSION_U__</em:version>
     <em:bootstrap>true</em:bootstrap>
 
-    <!-- for running custom screenshot binaries -->
-    <em:unpack>true</em:unpack>
-
     <!-- Front End MetaData -->
     <em:name>mozscreenshots</em:name>
     <em:description>Take screenshots of Mozilla applications in various UI configurations.</em:description>