Truth 0.37

• Delete Subject.failureStrategy. Use Subject.fail*.
• Delete Truth.THROW_ASSERTION_ERROR and TruthJUnit.throwAssumptionError(). Use Truth.assert_() and TruthJUnit.assume() (and methods like fail() and about(...).that(...) on the resulting objects).
• Delete SubjectFactory and CustomSubjectBuilderFactory. Use nested types Subject.Factory and CustomSubjectBuilder.Factory, which accept new type FailureMetadata rather than FailureStrategy.
• Make some Subject constructors protected now that they're useful only from subclasses.
• Prevent subclassing of DefaultSubject entirely: Use Subject.
• Enhanced our stripping of stack traces.