(Issue #16) Variable change notification support.

- new api now accepts functions and treats them as callbacks for change notifications
- solver batches all changes per solution and notifies callbacks
- currently has minimum information set: we could include old values, notice when a variable is new, etc.
Update Node.js test targets on Travis
Initial Component.io packaging
Ignore build artifacts from Component
Missing semicolons
Add a parser-based solving example
Fix typos in README.
Tests broke with most recent chai v1.8.x
Merge pull request #40 from pdubroy/master

Fix typos in README.
Merge pull request #35 from asolove/16-variable-change-notification

(Issue #16) Variable change notification support.
Merge pull request #37 from bergie/patch-1

Update Node.js test targets on Travis
Merge pull request #38 from bergie/master

Package as a Component
Manual merge of @slightlyoff updated master