Starting some unit tests using Mocha and Should

The tests trigger #20 where we crash when calling `.input()` or `.output()`
without using the `new` operator.
Throw when the new operator is omitted

Fixes #20 thanks to a tip from @agoode pointing me towards some great sample code:
constructor://github.com/kkaefer/node-cpp-modules/blob/master/06_objects/modulename.cpp
Added some tests for getPortName
Merge pull request #39 from drewish/ensure-new

Starting some unit tests and fixing crash when `new` is omitted