Stop testing Dartium (#47)

* only test on master branch
diff --git a/.travis.yml b/.travis.yml
index 8d63d09..2ea8538 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,20 +1,20 @@
 language: dart
-sudo: false
+
 dart:
   - dev
-cache:
-  directories:
-    - $HOME/.pub-cache
+
 dart_task:
   - test: --platform vm
   # No parallelism on Firefox (-j 1)
   # Causes flakiness – need to investigate
   - test: --platform firefox -j 1
-  - test: --platform dartium
-    install_dartium: true
   - dartanalyzer
   - dartfmt
-matrix:
-  exclude:
-    - dart: 1.22.1
-      dart_task: dartfmt
+
+# Only building master means that we don't run two builds for each pull request.
+branches:
+  only: [master]
+
+cache:
+  directories:
+    - $HOME/.pub-cache
diff --git a/pubspec.yaml b/pubspec.yaml
index 3b9bac4..3c9467f 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: async
-version: 2.0.4
+version: 2.0.5-dev
 author: Dart Team <misc@dartlang.org>
 description: Utility functions and classes related to the 'dart:async' library.
 homepage: https://www.github.com/dart-lang/async