Added unpin function

Let's users remove pins that are no longer necessary to keep on their
board.  Working on a system to keep track of pins and functions to
create/remove boards.
Update README.md
fix typo in unpin
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Added a function to edit pins

The function is called repin.  Might change that 'cuz I think it's a
little bit confusing.
Update README.md for repin
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added board functions, changed naming convention

- Added the ability to add, delete, and update boards.
- Changed the naming conventions for more accurate descriptions
Update README.md for board functions
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Update index.js

fixed an error
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Removed the need for boardId

a user can now either use boardId OR boardurl
Removed getPins, because it's not finished yet.
Update README.md
Update README.md
Merge pull request #1 from ivebencrazy/master

Merging in new functionality.  Once I've done some testing I'll release a new version to npm