Support Dart 2 gold (#58)

Cleanup .gitignore, .status, codereview.settings, analysis_options.yaml
Run browser tests on travis in serial
Prepare to release 2.0.6

Fixes https://github.com/dart-lang/crypto/issues/57
diff --git a/.gitignore b/.gitignore
index 25a1df3..79f51c3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,9 +1,3 @@
-.buildlog
-.DS_Store
-.idea
-.pub/
-.settings/
-build/
-packages
+.dart_tool
 .packages
 pubspec.lock
diff --git a/.status b/.status
deleted file mode 100644
index 059fb47..0000000
--- a/.status
+++ /dev/null
@@ -1,14 +0,0 @@
-# Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
-# for details. All rights reserved. Use of this source code is governed by a
-# BSD-style license that can be found in the LICENSE file.
-
-# Skip non-test files ending with "_test".
-packages/*: Skip
-*/packages/*: Skip
-*/*/packages/*: Skip
-*/*/*/packages/*: Skip
-*/*/*/*packages/*: Skip
-*/*/*/*/*packages/*: Skip
-
-test/sha1_test.dart: Pass, Slow
-test/sha256_test.dart: Pass, Slow
diff --git a/.travis.yml b/.travis.yml
index f433179..4681944 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,7 +5,7 @@
 
 dart_task:
   - test: -p vm
-  - test: -p firefox
+  - test: -p firefox -j 1
   - dartfmt
   - dartanalyzer
 
diff --git a/analysis_options.yaml b/analysis_options.yaml
index 2592ade..5a0e83e 100644
--- a/analysis_options.yaml
+++ b/analysis_options.yaml
@@ -1,5 +1,3 @@
-analyzer:
-  strong-mode: true
 linter:
   rules:
     # Errors
diff --git a/codereview.settings b/codereview.settings
deleted file mode 100644
index 6a07542..0000000
--- a/codereview.settings
+++ /dev/null
@@ -1,3 +0,0 @@
-CODE_REVIEW_SERVER: http://codereview.chromium.org/
-VIEW_VC: https://github.com/dart-lang/crypto/commit/
-CC_LIST: reviews@dartlang.org
diff --git a/pubspec.yaml b/pubspec.yaml
index 0b974b0..2df720d 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,10 +1,10 @@
 name: crypto
-version: 2.0.5
+version: 2.0.6
 author: Dart Team <misc@dartlang.org>
 description: Library of cryptographic functions.
 homepage: https://www.github.com/dart-lang/crypto
 environment:
-  sdk: '>=2.0.0-dev.17.0 <2.0.0'
+  sdk: '>=2.0.0-dev.17.0 <3.0.0'
 dependencies:
   collection: '^1.0.0'
   convert: '>=1.0.0 <3.0.0'