Bump codecov to latest version

Codecov 0.1.x were yanked from rubygems, causing installation of
cs_comments_service to fail.

The changes here were created by running `bundle update codecov`.

Fixes #322

Gemfile.lock

@@ -30,11 +30,12 @@ GEM
     bson (4.7.0)
     bson_ext (1.5.1)
     builder (3.2.3)
-    codecov (0.1.10)
+    codecov (0.2.6)
+      colorize
       json
       simplecov
-      url
     coderay (1.1.1)
+    colorize (0.8.1)
     concurrent-ruby (1.1.5)
     crack (0.4.3)
       safe_yaml (~> 1.0.0)
@@ -46,7 +47,7 @@ GEM
       mongoid (>= 3.0, < 8)
       mongoid-compatibility (>= 0.4.0)
     diff-lcs (1.3)
-    docile (1.1.5)
+    docile (1.3.2)
     domain_name (0.5.20170404)
       unf (>= 0.0.5, < 1.0.0)
     elasticsearch (1.1.2)
@@ -88,7 +89,7 @@ GEM
       domain_name (~> 0.5)
     i18n (0.9.5)
       concurrent-ruby (~> 1.0)
-    json (2.1.0)
+    json (2.3.1)
     kgio (2.11.0)
     listen (3.1.5)
       rb-fsevent (~> 0.9, >= 0.9.4)
@@ -175,11 +176,10 @@ GEM
     ruby_dep (1.5.0)
     safe_yaml (1.0.4)
     shellany (0.0.1)
-    simplecov (0.14.1)
-      docile (~> 1.1.0)
-      json (>= 1.8, < 3)
-      simplecov-html (~> 0.10.0)
-    simplecov-html (0.10.1)
+    simplecov (0.19.0)
+      docile (~> 1.1)
+      simplecov-html (~> 0.11)
+    simplecov-html (0.12.2)
     sinatra (1.4.8)
       rack (~> 1.5)
       rack-protection (~> 1.4)
@@ -198,7 +198,6 @@ GEM
     unicorn (5.3.1)
       kgio (~> 2.6)
       raindrops (~> 0.7)
-    url (0.3.2)
     webmock (3.0.1)
       addressable (>= 2.3.6)
       crack (>= 0.3.2)