Add Gemfile to Travis matrix

Author: root

Diff for: .travis.yml

@@ -13,8 +13,10 @@ matrix:
   include:
     - rvm: 2.2.0
       env: REDMINE_VERSION=3.0.0 DATABASE_ADAPTER=mysql
+      gemfile: Gemfile
     - rvm: 2.2.0
       env: REDMINE_VERSION=3.0.0 DATABASE_ADAPTER=postgresql
+      gemfile: Gemfile
 env:
   global:
     - REDMINE_LANG=en