Add projectSuffix option

[niktekusho]

Since #35 is still open, I thought I could finally resolve it maintaining the current behavior (as of 2.0.0) of adding the 'nodejs' suffix by default.

The option for controlling it is called projectSuffix, but feel free to change it to something you think is more appropriate.

I added 3 test cases which should cover all the cases I thought of:

1. compatibility: maintain the 2.0.0 behavior when not specifying the projectSuffix, so it will add the 'nodejs' suffix;
2. new: specifying an empty string should disable the suffix;
3. new: specifying a custom suffix should just use it instead of 'nodejs'.

I also updated the README with the new option specifics (added an Examples subsection).

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Fixes #35

[niktekusho]

I made major updates on the README and on test.js (as you required). I now think that maybe the examples on the README are not worth keeping since I don't think they explain the option that much better. Waiting for your review just in case. 😄

[niktekusho]

Friendly bump!
(I might have messed up with the review I resolved)