[maven-release-plugin] prepare for next development iteration
Ensure static query params are being appended properly.

Closes #212.
Dependency updates.
Merge pull request #215 from square/jw/static-query

Ensure static query params are being appended properly.
Handle nulls correctly for all parameters.

Closes #210.
Merge pull request #214 from square/jw/nulls

Handle nulls correctly for all parameters.
Merge pull request #216 from square/jw/gson-update

Dependency updates.
Allow uppercase letters in path parameters.
Merge pull request #218 from square/jw/earl

Allow uppercase letters in path parameters.
Prepare version 1.0.2.
[maven-release-plugin] prepare release parent-1.0.2
[maven-release-plugin] prepare for next development iteration
Add hook for customizing exceptions

The exceptions can be customized via a new ErrorHandler class, which is
responsible for returning customized exceptions during synchronous
requests.
Forbid returning null from error handler.

A bunch of code style and test clean-up as well.
Code style cleanup.
Be null.
Rename samples/ to retrofit-samples/

Also move it to its own groupId.
fix issue #227: permit use when servers or intermediaries mistakingly miss Content-Type header
Merge pull request #229 from adriancole/graceful-when-missing-mimetype

permit use when servers or intermediaries miss Content-Type header
Introduce `RequestInterceptor` to replace `RequestHeaders`.

In addition to global headers (which were doable before), this allows for global
path param replacement in URLs.

This has cropped up in a few APIs over the internet and we're traditionally not provided
a good path to implementation. Before you would have to manually move the global param
around your application to every method call site onto a Retrofit interface. This new
interface provides a single place to manage these global params along with other
global headers (such as for authentication).

Given:

    @GET("/show/{apiKey}/{showId}/episodes")
    List<Episode> episodes(@Path("showId") String showId)

Usage:

    class FooInterceptor implements RequestInterceptor {
      @Inject @ApiKey String apiKey;

      @Override public void intercept(RequestFacade request) {
        request.addPathParam("apiKey", apiKey);
      }
    }

This also has the added benefit of saving an extra `List` allocation for global headers
since they are now set directly on the underlying `Request` via the facade interface.