Change HTTP handler to whitelist network errors

Instead of (dangerously) whitelisting errors to reraise, this changes
the HTTP handler to explicitly list the raised exceptions for which the
exceptions should be swallowed.

Fundamentally, this changes handling of unknown errors (such as any Java
error in JRuby) to not be swallowed.
Capture OpenSSL errors, to allow retry for those as well
Merge pull request #282 from grddev/networking_errors

Change HTTP handler to whitelist network errors