Change private access modifiers for constants in MediaType

[scazacioc]

Change access modifier to public for

private static final String APPLICATION_TYPE = "application";
private static final String AUDIO_TYPE = "audio";
private static final String IMAGE_TYPE = "image";
private static final String TEXT_TYPE = "text";
private static final String VIDEO_TYPE = "video";

private static final String WILDCARD = "*";

[cgdecker]

Is there a particular reason you want these made public? I'm not necessarily opposed, but it would mean having a mix of public MediaType and String constants in the class, which could be awkward. We'd also need Javadoc on the public fields, etc.

[scazacioc]

The change is related to these issues : https://github.com/google/guava/issues/5794