Whole bunch of changes

Run sync within a SQL transaction, so that no partial sync happens

Don't abort on SQL errors, but print ERROR notice

Exit with code 1 when any ERRORs were logged

Silence the test suite, so that test runs are more clearly

Use PG queries instead of psql in test. This is more flexible
than parsing text outputs per Regexp.

lib/pg_ldap_sync/logger.rb

@@ -0,0 +1,24 @@
+require 'logger'
+
+module PgLdapSync
+class Logger < ::Logger
+  def initialize(io, counters)
+    super(io)
+    @counters = {}
+  end
+
+  def add(severity, *args)
+    @counters[severity] ||= 0
+    @counters[severity] += 1
+    super
+  end
+
+  def had_logged?(severity)
+    @counters[severity] && @counters[severity] > 0
+  end
+
+  def had_errors?
+    had_logged?(Logger::FATAL) || had_logged?(Logger::ERROR)
+  end
+end
+end