Upgrade premailer-rails from 1.9.0 to 1.9.2

Includes compatibility with Rails 5.

Changelog:
https://github.com/fphilipe/premailer-rails/blob/master/CHANGELOG.md#v19
2

Working towards #14286.

Gemfile.lock

@@ -145,7 +145,7 @@ GEM
     crack (0.4.3)
       safe_yaml (~> 1.0.0)
     creole (0.5.0)
-    css_parser (1.3.7)
+    css_parser (1.4.1)
       addressable
     d3_rails (3.5.11)
       railties (>= 3.1.0)
@@ -559,8 +559,8 @@ GEM
     premailer (1.8.6)
       css_parser (>= 1.3.6)
       htmlentities (>= 4.0.0)
-    premailer-rails (1.9.0)
-      actionmailer (>= 3, < 5)
+    premailer-rails (1.9.2)
+      actionmailer (>= 3, < 6)
       premailer (~> 1.7, >= 1.7.9)
     pry (0.10.3)
       coderay (~> 1.1.0)