Move to gulp-sass 3.0.0

I have seen the following error on gulp-sass 2.3.2:
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! node-sass@3.13.1 postinstall: `node scripts/build.js`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the node-sass@3.13.1 postinstall script.

Googling this appears to be a common problem and the recommendation
is to move to gulp-sass 3.0.0

Tested: Running GUI locally
Change-Id: If8ae76a0184f9abf16c3c7d71446a5bc7bf5e8be
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
diff --git a/package.json b/package.json
index 5e793b8..73cc34a 100644
--- a/package.json
+++ b/package.json
@@ -18,7 +18,8 @@
   "contributors": [
     "Iftekharul Islam <iffy.ryan@ibm.com>",
     "Michael Davis <michael.s.davis@ibm.com>",
-    "Ed Tanous <ed.tanous@intel.com>"
+    "Ed Tanous <ed.tanous@intel.com>",
+    "Gunnar Mills <gmills@us.ibm.com>"
   ],
   "files": [
     "dist"
@@ -76,7 +77,7 @@
     "gulp-rename": "^1.2.2",
     "gulp-rev": "^0.4.0",
     "gulp-rev-replace": "^0.4.2",
-    "gulp-sass": "^2.3.2",
+    "gulp-sass": "^3.0.0",
     "gulp-strip-debug": "^1.0.2",
     "gulp-uglify": "^1.2.0",
     "gulp-useref": "^1.2.0",