Fix client side integration tests

[bendrucker]

As discussed in #33

Previously:

• Pass in every global tape depends on
• Create a new test runner for every suite

Now:

• Create a single runner and pass a "test" global to every test
• Use named, nested tests for more readable output

Bonus:

• Tests pass on iojs!
• Add 0.12 and iojs to Travis

[thlorenz]

Perfect, LGTM. Please merge to master. No publish needed at this point. Thanks.