style(swig.js, ngtemplates.js): missing use strict statement
chore(jscs, jshint): lint chore related files

Chore files (build/**/*.js) were not in any linting task, so
this commit lints them both via jscs and jshint.
chore(package.json): update grunt-jscs-checker

grunt-jscs-checker v0.6.0 is out, so we'll adapt the task options
to match the changes.
chore(jscs, jshint): fix chore files

Prior to d06390d7dead510e22ae03b582de845a125296c0, we did
not have linting enabled for chore related files.
This commit fixes the linting problems introduced in that commit.