Fix bug in `nextUntil`

Ensure that the `nextUntil` method operates over every element in the
collection, and avoid returning a collection with duplicate elements.
Fix bug in `prevUntil`

Ensure that the `prevUntil` method operates over every element in the
collection, and avoid returning a collection with duplicate elements.
Fix bug in `next`

Ensure that the `next` method operates over every element in the
collection.
Fix bug in `nextAll`

Ensure that the `nextAll` method operates over every element in the
collection, and avoid returning a collection with duplicate elements.
Fix bug in `prev`

Ensure that the `prev` method operates over every element in the
collection.
Fix bug in `prevAll`

Ensure that the `prevAll` method operates over every element in the
collection, and avoid returning a collection with duplicate elements.
Merge pull request #340 from jugglinmike/nexts-and-prevs

Fix bugs in "next*" and "prev*" methods
Release 0.13.0
drop support for node 0.6
Remove unecessary DOM maintenance logic

This logic was incorporated into the `parse` module's `update` method in
commmit 973c8f44d56cd6051284eaaf83b3dc0d34ec2eaa.
Merge pull request #351 from jugglinmike/redundant-code

Remove unecessary DOM maintenance logic
Fix bug in Cheerio function

When used with a context set through the static `load` method, the
instance will already have numeric properties corresponding to the
originally-loaded nodes. These properties should be overwritten by the
elements passed to the Cheerio function in all cases.
Merge pull request #342 from jugglinmike/fix-select-with-context

Fix bug in Cheerio function
Update package.json

Changed underscore to v 1.5.3
Update package.json

Don't think underscore v1.5.3 is quite out there yet...
added parentsUntil method
Filter duplicates and add  more tests for parentsUntil method