Use `Throwable.addSuppressed()` directly and/or via try-with-resources

[cowtowncoder]

Looks like JDK 7 can solve a nasty problem with secondary exceptions thrown when flushing/closing encoders (like with Avro), by addSuppressed() method. Since we still try to work with Android, at least for 2.8, let's add method(s) via Java7Support abstraction.

[cowtowncoder]

FWIW, Throwable.addSuppressed() was added in Android 4.4 (API level 19):

http://developer.android.com/reference/java/lang/Throwable.html#addSuppressed(java.lang.Throwable)

http://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels

So we can probably just call it directly with Jackson 2.9.