Integrating Dart 2.8 compatible version of mock_request (#496)

* Dart 2.8 compatible version of mock_request

* third_party doesn't work with docker

* Test on both dart stable and dev
diff --git a/.travis.yml b/.travis.yml
index 29a5c1f..cab8fe3 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,9 +4,7 @@
 dart:
   # Keep this value aligned with min SDK value in pubspec.yaml and FROM line of Dockerfile
   - "2.7.2"
-  # TODO(devoncarew): commented out due to
-  # https://github.com/dart-lang/dart-pad/issues/1002
-  #- dev
+  - dev
 
 # Speed up builds by using containerization. Disable this if you need to use
 # sudo in your scripts.
diff --git a/pubspec.lock b/pubspec.lock
index 9529ecd..6ebacfb 100644
--- a/pubspec.lock
+++ b/pubspec.lock
@@ -77,7 +77,7 @@
       name: build_daemon
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.3"
+    version: "2.1.4"
   build_resolvers:
     dependency: transitive
     description:
@@ -382,10 +382,12 @@
   mock_request:
     dependency: "direct dev"
     description:
-      name: mock_request
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "1.0.6"
+      path: "."
+      ref: HEAD
+      resolved-ref: "7a21837c234f9328df8de0e0cf74893d4a82df93"
+      url: "https://github.com/domesticmouse/mock_request.git"
+    source: git
+    version: "1.0.7"
   multi_server_socket:
     dependency: transitive
     description:
@@ -420,7 +422,7 @@
       name: package_config
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.9.2"
+    version: "1.9.3"
   package_resolver:
     dependency: transitive
     description:
diff --git a/pubspec.yaml b/pubspec.yaml
index 5049351..62b4e7c 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -33,7 +33,11 @@
   coverage: ^0.13.0
   discoveryapis_generator: ^0.9.11
   grinder: ^0.8.0
-  mock_request: ^1.0.6
+  # TODO(brettmorgan): return to mock_request pub package after it is
+  # published with https://github.com/thosakwe/mock_request/pull/3
+  # mock_request: ^1.0.6
+  mock_request:
+    git: https://github.com/domesticmouse/mock_request.git
   pedantic: ^1.9.0
   shelf_router_generator: ^0.7.0+1
   synchronized: ^2.1.0