Added tests for broken << operator.
First try to fix broken << operator.  Some tests still fail in sqlite, but fixes appear to work
when manually tested in PostgreSQL.  Checking in so I can clone on a CentOS box where PostgreSQL
tests can be run.
Added Travis CI icon for inetdavid/closure_tree fork.
Remove stderr message.  See if I can reduce TravisCI matrix for now till I narrow down the problems.
Ensure order_value is always set if order_is_numeric?.  (With tests.)
Restore remainder of Travis test matrix after passing with Ruby 1.9.3/Rails 3.2 on all databases
Remove link to Travis test icon for inetdavid/closure_tree from README.md
Add tests to confirm two new issues (deletion failures and sort_order issues)
unhide the failures
rebuild now forces sort order on save and on reparenting
preparing 4.4.0
fixed tests
fixed tests
Merge branch 'master' into no_nil_order_values

Conflicts:
	CHANGELOG.md
	lib/closure_tree/version.rb
	spec/parallel_spec.rb
Merge branch 'pr99' into no_nil_order_values
Merge branch 'master' into no_nil_order_values
constrain builds while I fix this [skip ci]
doc twiddles
fixed sort order on sqlite
fix query counting, which broke parallel tests (but only for MySQL (?!))
no-op