Verify All Memory Related Leaks and crashes

[cowboyd]

Because of the way The Ruby Racer handled references for Ruby objects embedded into V8, where JavaScript is the only runtime that holds a reference, there many GC edge cases that were hard to get right. This lead to persistent instabilities relating to memory and garbage collection.

Newer versions of V8 make this easier to track by letting the embedder do book-keeping at the both the Isolate and Context levels, so that #348 his able to handle these issues.

Create a testcase and verify that the following tickets are resolved by #348

#153 #169 #176 #187 #201 #206 #260 #265 #274 #345 #330 #328 #326 #320 #317 #316 #309 #300 #299