travis: drop ruby 1.8.7 tests

The Ruby 1.8.7 tests have been broken for ages, and it's unlikely anyone
will do the work to restore support for the tests. Drop them from the suite
to save Travis CI from doing work for nothing on every commit.

.travis.yml

@@ -10,10 +10,6 @@ bundler_args: --without rake
 matrix:
   fast_finish: true
   include:
-    - rvm: 1.8.7
-      env: PUPPET_GEM_VERSION="~> 2.7.0"
-    - rvm: 1.8.7
-      env: PUPPET_GEM_VERSION="~> 3.0"
     - rvm: 1.9.3
       env: PUPPET_GEM_VERSION="~> 3.0"
     - rvm: 2.0.0
@@ -22,10 +18,5 @@ matrix:
       env: PUPPET_GEM_VERSION="~> 3.0"
     - rvm: 2.1.0
       env: PUPPET_GEM_VERSION="~> 4.0"
-  allow_failures:
-    - rvm: 1.8.7
-      env: PUPPET_GEM_VERSION="~> 2.7.0"
-    - rvm: 1.8.7
-      env: PUPPET_GEM_VERSION="~> 3.0"
 notifications:
-  email: false  
+  email: false