Making TestingUtils abstract so that JUnit ignores

initializationError(retrofit.http.TestingUtils)
java.lang.Exception: No runnable methods
Using Response in readme instead of SimpleResponse
Only using getErrorStream() for status >= 400
Replacing Response with MyJsonObj in README

Using MyJsonObj to make it more clear it is a custom type
Use standard exception cause handling in RetrofitError.

Improves RetrofitError.toString() output.
Update sample name to reflect behavior.
Merge pull request #175 from square/jw/fix-sample

Update sample name to reflect behavior.
Fix for 204 'No Content' responses.
Merge pull request #176 from codebutler/master

Fix handling of 204 No Content responses
Merge pull request #170 from ransombriggs/simpleResponseReadmeFix

Using Response in readme instead of SimpleResponse
Merge pull request #169 from ransombriggs/fixingTestsFromMaven

Making TestingUtils abstract so that JUnit ignores
Merge pull request #171 from ransombriggs/errorStreamFix

Only using getErrorStream() for status >= 400
Merge branch 'master' of git://github.com/square/retrofit