Add analyze task to build configuration

.travis.yml

 matrix:
   include:
+    # Job 1) Run analyzer
+    - os: linux
+      env:
+        - SHARD=Analyze
+      sudo: false
+      addons:
+        apt:
+          # Flutter depends on /usr/lib/x86_64-linux-gnu/libstdc++.so.6 version GLIBCXX_3.4.18
+          sources:
+            - ubuntu-toolchain-r-test # if we don't specify this, the libstdc++6 we get is the wrong version
+          packages:
+            - libstdc++6
+            - fonts-droid
+      before_script:
+        - git clone https://github.com/flutter/flutter.git $HOME/flutter
+        - export PATH=$HOME/flutter/bin:$HOME/flutter/bin/cache/dart-sdk/bin:$PATH
+        - flutter doctor
+      script:
+        - flutter analyze
+    # Job 2) Build the Android axample application (.apk)
     - os: linux
       env:
         - SHARD="Build example apks"
@@ -21,7 +41,7 @@ matrix:
       script:
         - cd ./example
         - flutter build apk
-    # Job 2) Build example IPAs
+    # Job 3) Build the iOS example Applications (.ipa)
     - os: osx
       env:
         - SHARD="Build example ipas"
@@ -35,4 +55,4 @@ matrix:
         - flutter build ios --no-codesign
 cache:
   directories:
-    - $HOME/.pub-cache
\ No newline at end of file
+    - $HOME/.pub-cache