Move run spec fakefs cleanup to correct spot.

Wasn't being cleaned up / deactivated for some specs,
which could leak fakefs activation into other specs
depending on order.
Reset MetricFu after each spec.

Class variable settings were leaking into
other specs and wreaking all sorts of havoc.
Update stubbed methods related to open in browser
Add file system stubs for rbx.
Use configure_metrics shortcut.
Fix for undefined json issues in specs.
Merge pull request #115 from robincurry/bug/random-test-order-fixes

Fix tests failing when config.order set to random