Remove upper case constants (#28)

Remove usage of upper-case constants.

Update SDK version.
Remove stable from Travis config.
diff --git a/.travis.yml b/.travis.yml
index 63f5e5e..7dee3cc 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,8 +2,6 @@
 
 dart:
   - dev
-  - stable
-
 dart_task:
   - test
   - dartanalyzer
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 51ae820..2372584 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.2.7+1
+
+* Updated SDK version to 2.0.0-dev.17.0
+
 ## 0.2.7
 
 * Require at least Dart SDK 1.24.0.
diff --git a/pubspec.yaml b/pubspec.yaml
index a8ac568..59efc1f 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,10 +1,10 @@
 name: shelf_static
-version: 0.2.7
+version: 0.2.7+1
 author: Dart Team <misc@dartlang.org>
 description: Static file server support for Shelf
 homepage: https://github.com/dart-lang/shelf_static
 environment:
-  sdk: '>=1.24.0 <2.0.0'
+  sdk: '>=2.0.0-dev.17.0 <2.0.0'
 dependencies:
   convert: '>=1.0.0 <3.0.0'
   http_parser: '>=0.0.2+2 <4.0.0'
diff --git a/test/basic_file_test.dart b/test/basic_file_test.dart
index 17f8018..6b5e005 100644
--- a/test/basic_file_test.dart
+++ b/test/basic_file_test.dart
@@ -34,8 +34,8 @@
     await d.dir('files', [
       d.file('test.txt', 'test txt content'),
       d.file('with space.txt', 'with space content'),
-      d.file('header_bytes_test_image', BASE64.decode(pngBytesContent)),
-      d.file('header_bytes_test_webp', BASE64.decode(webpBytesContent))
+      d.file('header_bytes_test_image', base64Decode(pngBytesContent)),
+      d.file('header_bytes_test_webp', base64Decode(webpBytesContent))
     ]).create();
   });