Update qless from 0.10.3 to 0.12.0

The old version of qless is incompatible with newer versions of Redis,
see seomoz/qless-core#64.

Update using 'bundle update --conservative qless' to avoid updating
other gems if possible.

Submissions caused the following error:

Redis::CommandError - ERR Error running script (call to ...): @user_script:925: @user_script: 925: Lua redis() command arguments must be strings or integers:
  app/workers/application_worker.rb:6:in `put'
  app/workers/judge_submission_worker.rb:24:in `judge'
  app/models/submission.rb:121:in `judge'
  app/controllers/problems_controller.rb:90:in `block in submit'
  app/controllers/problems_controller.rb:88:in `submit'
  lib/rack/response_timer.rb:12:in `_call'
  lib/rack/response_timer.rb:7:in `call'

Now all all the tests pass.

Gemfile.lock

@@ -77,7 +77,7 @@ GEM
       public_suffix (>= 2.0.2, < 4.0)
     afm (0.2.2)
     arel (4.0.2)
-    atomic (1.1.99)
+    atomic (1.1.101)
     avl_tree (1.2.1)
       atomic (~> 1.1)
     backup (3.4.0)
@@ -134,7 +134,7 @@ GEM
       thor (~> 0.19.4)
       tins (~> 1.6)
     crass (1.0.3)
-    daemons (1.2.6)
+    daemons (1.3.1)
     debug_inspector (0.0.3)
     decorators (1.0.5)
       railties (>= 3.0.19)
@@ -150,7 +150,7 @@ GEM
       unf (>= 0.0.5, < 1.0.0)
     erubi (1.7.0)
     erubis (2.7.0)
-    eventmachine (1.2.5)
+    eventmachine (1.2.7)
     execjs (2.7.0)
     facebox-rails (0.2.0)
       railties (>= 3.0, < 5.0)
@@ -160,7 +160,7 @@ GEM
     factory_girl_rails (4.9.0)
       factory_girl (~> 4.9.0)
       railties (>= 3.0.0)
-    faraday (0.13.1)
+    faraday (0.15.4)
       multipart-post (>= 1.2, < 3)
     ffi (1.9.18)
     foreman (0.84.0)
@@ -174,7 +174,7 @@ GEM
       activesupport (>= 3.2, < 5)
     hashery (2.1.2)
     hashie (3.5.7)
-    hitimes (1.2.6)
+    hitimes (1.3.1)
     hive_geoip2 (0.1.2)
     http-cookie (1.0.3)
       domain_name (~> 0.5)
@@ -253,14 +253,14 @@ GEM
     pygments.rb (0.5.4)
       posix-spawn (~> 0.3.6)
       yajl-ruby (~> 1.1.0)
-    qless (0.10.3)
+    qless (0.12.0)
       metriks (~> 0.9)
-      redis (>= 2.2)
+      redis (>= 2.2, < 4.0.0.rc1)
       rusage (~> 0.2.0)
-      sentry-raven (~> 0.4)
-      sinatra (~> 1.3)
+      sentry-raven (~> 0.15.6)
+      sinatra (>= 1.3, < 2.1)
       statsd-ruby (~> 1.3)
-      thin (~> 1.6.4)
+      thin (~> 1.6)
       thor (~> 0.19.1)
       vegas (~> 0.1.11)
     rack (1.5.5)
@@ -382,10 +382,10 @@ GEM
     therubyracer (0.12.3)
       libv8 (~> 3.16.14.15)
       ref
-    thin (1.6.4)
+    thin (1.7.2)
       daemons (~> 1.0, >= 1.0.9)
       eventmachine (~> 1.0, >= 1.0.4)
-      rack (~> 1.0)
+      rack (>= 1, < 3)
     thor (0.19.4)
     thread_safe (0.3.6)
     tilt (2.0.8)