Disallow explicit signs in java.sql.Timestamp#valueOf()

The implementation was cleaned up:
- removed useless checks and improved a few other
- fixed variable names
- fixed badTimestampString

Bug: 5239391
Change-Id: I51ea2ba848b0c2d2d2f26807a1c56e7e015ef9f4

Conflicts:
	luni/src/main/java/java/sql/Timestamp.java
Fix UUID#parseString in the presence of explicit + signs.

Also added Long#parsePositiveLong(String, int).

Bug: 5239391
Change-Id: Iaa0bbd3a7f8a13c3e48abb1a7e7508e48615b11c

Conflicts:
	luni/src/test/java/libcore/java/util/UUIDTest.java
Support explicit + in Byte, Short, Integer, Long.

Bug: 5239391
Change-Id: I2b25228815d70d570d537db0ed9b5b759f25b5a3

Conflicts:
	luni/src/main/java/java/lang/Integer.java
	luni/src/main/java/java/lang/Long.java
	luni/src/test/java/libcore/java/lang/IntegerTest.java
	luni/src/test/java/libcore/java/lang/LongTest.java
SSLEngine: update harmony tests

The old tests were broken and difficult to debug because of catching
exceptions and calling fail()

Change-Id: Idad6774e5f0839242b0667be1a25784b7ec70aef