.gitignore, package.json
A way to run tests
First failing spec

"Error: Cannot find module './string_num_sum'" -- we are trying to
require a module that does not exist.

Normally I don't commit failing specs, but I thought it would be
interesting for someone to be able to read through this repository
commit by commit if they so desired.
Failure 2: object is not a function

We now have the file that represents the module, but it is exporting an
object (an empty {}) instead of a function.
Failure 3: expected undefined to equal 0

Note that I had an error in my test.  :)

The function is implemented, so that error goes away, but it does not
return anything.
Pass 1: simplest solution

We will make this code fail shortly, because it's obviously ridiculous.
Failure 4: expected 0 to be 123
Pass 2: parseInt
Failure 5: When a base is not provided to parseInt
Pass 3: parseInt with a base
Failure 6: does not handle non-numeric characters
Pass 4: ignore alpha characters
Failure 7: expected 2430 to be 432
Failure 8: previously passing test fails

I did not realize that .reduce() is now part of javascript.  No need for
underscore yet!

However, the new code cannot handle nulls, since parseInt will return
NaN and add() does not handle it.
Pass 5: working solution

Filter out NaN, sum away.

There may be a better solution in the future, but at least we've defined
an interface and can have some amount of confidence when refactoring in
the future.

Underscore is still not needed; .filter() is standard in node!