add cmake (#73)

* add cmake

* lock ubuntu version

Author: gengjiawen

Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu
+FROM ubuntu:18.04
 
 LABEL Description="This image provides a base Android development environment for React Native, and may be used to run tests."
 
@@ -77,6 +77,7 @@ RUN curl -sS https://dl.google.com/android/repository/${SDK_VERSION} -o /tmp/sdk
         "platforms;android-$ANDROID_BUILD_VERSION" \
         "build-tools;$ANDROID_TOOLS_VERSION" \
         "add-ons;addon-google_apis-google-23" \
+        "cmake;3.10.2.4988404" \
         "system-images;android-19;google_apis;armeabi-v7a" \
         "extras;android;m2repository" \
         "ndk;$NDK_VERSION" \