0.9.20

• upgrade Bouncy-Castle to 1.56 http://bouncycastle.org/releasenotes.html
  (additional security and robustness with 10 CVEs submitted as a result)
• add a dummy SSLContext#security_level= implementation
• no dup-ing for SSLContext/SSLSocket and X509 Store/StoreContext
• implement PKey initialize_copy (dup-ing)
• digest can be passed in as a String on PKey#sign/verify
• DSA+SHA1 is actually a supported algorithm
• reset signed-request -> sub-sequent req.verify will work correctly
• allow for digest name to be passed into Cert#sign
• be less fatal on Java 9
  won't attempt reflective SPIs when accessibility checks fail!
• remove obsolete (deprecated) renamed classes
• verify correct WaitReadable is raised on connect_nonblock (jruby/jruby#1716)
• non-connected ssl socket raises EPIPE on connect_nonblock (MRI compat)
• fine to close a SSLSocket which is not-yet-connected (like in MRI)
• fix NPE when reading private keys (with passwd) (jruby/jruby#1784)