test: increase timeout for browserify
test: add `global.navigator` for browser tests

The debug module uses `navigator.userAgent` to detect whether the
browser support colors in console logs.
test: ensure sandbox dir is present

Fix test/browser.test.js failing on CI due to sandbox dir not present
on the first run.
Merge pull request #36 from strongloop/feature/fix-CI-build

test: fix failures on CI