feat: add escapedName to parsed Result

[nexdrew]

escapedName URI-encodes the slash for scoped names such that @foo/bar becomes @foo%2fbar. For unscoped names, escapedName should just match name, either null or otherwise.

The idea is that anywhere you would use name when talking to a registry, you should now use escapedName instead. This should eliminate the need for duplicating lines like this across multiple repos/packages/modules that need to parse a package name when working with a registry, which is something we do quite often among open and closed source code at npm. This little package seems an ideal place to centralize this logic.

When implementing this, I considered a few different options:

1. Using Object.defineProperty to add escapedName as a getter method that was always derived from name, conditionally escaping based on scope

   This kept things simple in terms of not needing to "follow" all the places in the logic where name and scope are set. Its drawback, however, was a hidden value when relying on Object.prototype.toString(), such as here, which resulted in output like:

   Result {
     escapedName: [Getter],
     raw: '@foo/bar',
     scope: '@foo',
     name: '@foo/bar',
     rawSpec: '',
     spec: 'latest',
     type: 'tag' }
   

   Which is obviously less than ideal.

2. Using a wrapper or decorator function to populate escapedName whenever res is returned.

   This fixed the toString() problem, but since the npa() function can actually return in a few different places, I ended up "following" the return statements rather than where name and scope are actually set. This seemed less than ideal since the it didn't make the relationship between the derived property and the original properties obvious.

So instead I opted to align the setting of escapedName in close proximity to the setting of scope and name in an explicit, procedural way.

[nexdrew]

It seems that builds have been failing or erring for Node 0.8 for quite some time, so please don't hold that against this PR. 😃

[othiym23]

To avoid confusion this should be in a separate commit (or PR; I think it may be time to standardize this code base).

[nexdrew]

Ok, good point, I will undo this.

[othiym23]

The CLI team is dropping support for 0.8 as of now, so I'll probably pull that from .travis.yml and we'll see what happens. A couple minor nits, but otherwise this looks good, and as a purely additive API, should be good to go once those nits have been addressed.

[coveralls]

Coverage increased (+0.3%) to 96.33% when pulling b8d31ba on nexdrew/escapedName into b39730c on master.

[nexdrew]

@othiym23 Attempted to address your concerns. Tests pass for me locally. Let me know if you see anything else.

[coveralls]

Coverage increased (+0.2%) to 96.262% when pulling 445438a on nexdrew/escapedName into b39730c on master.

[coveralls]

Coverage increased (+0.2%) to 96.262% when pulling a7588aa on nexdrew/escapedName into b39730c on master.

[othiym23]

Rebased and landed as e92fcc9. Thanks, Andrew!