Updates to rake 10
Supports mocha 0.13.0 which removed "mocha/object"
Backs out aruba upgrade as it seems to be broken on JRuby
This reverts commit ed121c0.
This reverts commit a3f45f9.
Bumps aruba version
* Preserves JRUBY_OPTS, making it easier to test in 1.9 mode locally.
Removes the need for `fakefs`
* `fakefs` is broken under rbx