Simplify a few arguments.length checks.
Add component.json to appease Bower.
Bump version number to appease Bower.
jam integration
updated src/package for future builds
More flexible XHR framework.

This is backwards-compatible, yet adds numerous features to d3.xhr. You can now:

  * Use standard node-style callbacks (fixes #473).
  * Abort in-flight requests.
  * Listen for progress events.
  * Listen for load, error and abort events separately.
  * Make POST requests (or any other method), including data.
  * Set arbitrary request headers.
  * Have multiple listeners on requests.
Slightly shorter fix for send(undefined).
Merge branch 'xhr-accept' of https://github.com/jasondavies/d3 into xhr2

Conflicts:
	src/core/xhr.js
Fix d3.json.
Add xhr.content; simplify type-specific requests.
Rename xhr.content to xhr.response.

The name content is a bit ambiguous since the request can post content, too.
Consume preset headers on open.
Make d3.xhr more declarative and less stateful.
Remove abort events.

Since the caller is the one aborting, it can handle its own notification.
Specify default Content-Type with data.

Also, headers should be case-insensitive.
Slightly safer check.
Inline constant.
Oops, forgot generated files.
More convenient d3.xhr interface.

Rather than setting the method and data, you can now call get or post.
Don't set a default Content-Type header.