Update jasmine-core

This updates our jasmine-core dependency to the latest version.
In v2.8, some of the output from test failures is much more legible
than in v2.6.

Change-Id: I56ac0aa47fdd18ac57108c1e481ef9269269da51

Author: joeyparrish

package.json

@@ -17,7 +17,7 @@
     "htmlhint": "yaniswang/HTMLHint#152a114f",
     "in-publish": "~2.0.0",
     "jasmine-ajax": "~3.3.1",
-    "jasmine-core": "~2.6.1",
+    "jasmine-core": "^2.8.0",
     "karma": "~1.6.0",
     "karma-chrome-launcher": "~2.0.0",
     "karma-coverage": "~1.1.1",