Merge remote branch 'apache:add-couch_log_twig-backend'

This closes #4

Signed-off-by: ILYA Khlopotov <iilyak@ca.ibm.com>
diff --git a/src/couch_log_twig.erl b/src/couch_log_twig.erl
new file mode 100644
index 0000000..fef3d50
--- /dev/null
+++ b/src/couch_log_twig.erl
@@ -0,0 +1,54 @@
+% Licensed under the Apache License, Version 2.0 (the "License"); you may not
+% use this file except in compliance with the License. You may obtain a copy of
+% the License at
+%
+%   http://www.apache.org/licenses/LICENSE-2.0
+%
+% Unless required by applicable law or agreed to in writing, software
+% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+% License for the specific language governing permissions and limitations under
+% the License.
+
+-module(couch_log_twig).
+
+-behaviour(couch_log).
+
+-export([
+    debug/2,
+    info/2,
+    notice/2,
+    warning/2,
+    error/2,
+    critical/2,
+    alert/2,
+    emergency/2,
+    set_level/1
+]).
+
+debug(Fmt, Args) ->
+    twig:log(debug, Fmt, Args).
+
+info(Fmt, Args) ->
+    twig:log(info, Fmt, Args).
+
+notice(Fmt, Args) ->
+    twig:log(notice, Fmt, Args).
+
+warning(Fmt, Args) ->
+    twig:log(warning, Fmt, Args).
+
+error(Fmt, Args) ->
+    twig:log(error, Fmt, Args).
+
+critical(Fmt, Args) ->
+    twig:log(crit, Fmt, Args).
+
+alert(Fmt, Args) ->
+    twig:log(alert, Fmt, Args).
+
+emergency(Fmt, Args) ->
+    twig:log(emerg, Fmt, Args).
+
+set_level(Level) ->
+    twig:set_level(Level).