Switch headers to come from an interface implementation.

This makes it much more easy to provide dynamic headers. Rather than dealing with a Provider, you can now have a concrete class implement this interface.

Closes #146.
Merge pull request #147 from square/jw/footers

Switch headers to come from an interface implementation.
Break up TypedBytes into TypedInput and TypedOutput.

Update Response to use TypedInput.

Closes #135.
Merge pull request #148 from square/jw/typed-things

Break up TypedBytes into TypedInput and TypedOutput.
Move packages.

* `retrofit.io` -> `retrofit.http.mime`
* `retrofit.android` -> `retrofit.http.android`
Merge pull request #149 from square/jw/package-move

Move packages.
Remove JSR-330 dependency in favor of our own annotations.

Closes #137.
Merge pull request #150 from square/jw/drop-jsr-330

Remove JSR-330 dependency in favor of our own annotations.
Follow-up @Name introduction.
Use TypedOutput for Requests.

Refs #141.
Disallow query params in the URL.
Merge pull request #153 from square/jw/weary-query

Disallow query params in the URL.
Provide a mutable server implementation. Update Server API to conform.
Merge pull request #156 from square/jw/point-to-things

Provide a mutable server implementation. Update Server API to conform.
Log request headers. Update response log format to match.
Merge pull request #157 from square/jw/log-request-more-like-yeah

Log request headers. Update response format to match.
Merge pull request #152 from square/jw/request-typed

Use TypedOutput for Requests.
Fix Url Escaping on GET Parameters

This patch fixes url escaping on url-encoded GET parameters. Query parameters will now be escaped. Test cases for common characters ?, #, and & are included.
Merge pull request #158 from campnic/escape_fix

Fix Url Escaping on GET Parameters
Add UrlConnection Client.

Use this on Android 2.2 and prior and when on the JVM.

Also update our sample to use GitHub contributors rather than the Twitter API because the latter is shutting down and subject to lame rate limiting when on common networks.

Bump some dependencies to their latest versions.