build: Update various devDependencies

* grunt-file-exists	0.1.1 -> 0.1.2
* grunt-jscs		0.8.1 -> 1.0.0
* karma-chrome-launcher	0.1.5 -> 0.1.7
* karma-coverage	0.2.6 -> 0.2.7
* q			1.1.1 -> 1.1.2
* qunitjs		1.16.0 -> 1.16.0

Change-Id: Iffdfe8fa6245e812acb719fc46c147f8211fded5
Merge "build: Update various devDependencies"