java.security.cert: update classes in java.security.cert (part 2)

Pulling upstream changes from OpenJDK version jdk8u60 classes
in java.security.cert

- Certificate#hashValue: cache the hash value as to avoid recomputation.
Use the Arrays#hash instead of a simple ad-hoc function.
- Certificate#verify(PublicKey, Provider): new method that just throws
UnsupportedOperationException.

This commit also contains cosmetic JavaDoc changes like
- Use of @code in place of <code> tags and use of a package-info.java in
place of a package.html file.
- Added comments.

Note not all classes in java.security.cert are updated:  X509CRL has more
significant changes and deserves a separate CL.

Change-Id: I44120f1b34c9dc3c062a5d01583bcc87fa2cd558
Test: make droid docs, vogar CertificateTest
Bug: 29631070

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