Added spec for new and old attributes syntax
Remove ruby 1.8.7 from travis test matrix

From what I understand, no one in the community still requires 1.8.7
support, and getting all of the tests to pass on Travis is a lot of work
for very little value. I'd be willing to accept PRs to get this passing,
but I'm inclined to drop support for ruby 1.8.7 in the next minor
version of Savon (eg: 2.4 or 2.5)
Remove last 1.8.7 ruby from travis test matrix
Add json gem for jruby on travis-ci
Remove ree from travis ci test matrix
Use message_tag rather than operation_name

Fixes #553
Version bump
Logging is off by default now

I think this makes a lot of sense for development, but few people
want this behavior at runtime. Will revisit documenting this change
if we see reports of Savon being difficult to debug.

Closes #545
Bump version to 2.4.0
Backport @moxley's fix to v2 branch
Merge remote-tracking branch 'skalar/version2' into version2
Merge remote-tracking branch 'upstream/version2' into version2

Conflicts:
	lib/savon/options.rb