Update Dockerfile (#1400)

* Update Dockerfile

reverted the INTERPRETER CHANGES

* Added a conditional for a prebuilt argument based on task type

* Added default arg and also conditional cmake argument

* Update .travis.yml

* Update Dockerfile

.ci/travis/ubuntu/Dockerfile

 FROM ubuntu:16.04
 
+#buildtype argument
+ARG buildtype=regular
+
 # nGraph dependencies
 RUN apt-get update && apt-get install -y \
   build-essential \
@@ -31,8 +34,12 @@ COPY . /root/ngraph
 RUN mkdir /root/ngraph/build
 WORKDIR /root/ngraph/build
 
-RUN cmake .. -DNGRAPH_CPU_ENABLE=FALSE -DNGRAPH_USE_PREBUILT_LLVM=TRUE \
-             -DNGRAPH_ONNX_IMPORT_ENABLE=TRUE -DCMAKE_INSTALL_PREFIX="~/ngraph_dist"
+RUN if  [ "$buildtype" = "interpreter" ] ; then \
+        cmake .. -DNGRAPH_CPU_ENABLE=FALSE -DNGRAPH_USE_PREBUILT_LLVM=TRUE -DNGRAPH_ONNX_IMPORT_ENABLE=TRUE\
+                 -DCMAKE_INSTALL_PREFIX="~/ngraph_dist";\
+    else \
+        cmake ..  -DNGRAPH_USE_PREBUILT_LLVM=TRUE -DNGRAPH_ONNX_IMPORT_ENABLE=TRUE -DCMAKE_INSTALL_PREFIX="~/ngraph_dist" ;\
+    fi
 
 RUN make
 RUN make install

.travis.yml

@@ -14,7 +14,12 @@ env:
   - TASK=python3_test
 
 before_install:
-  - docker build -t test_ngraph -f .ci/travis/ubuntu/Dockerfile .
+  - |
+    if [ "TASK" == "cpp_test" ]; then 
+      docker build -t test_ngraph -f .ci/travis/ubuntu/Dockerfile .
+    else
+      docker build -t test_ngraph -f .ci/travis/ubuntu/Dockerfile --build-arg buildtype=interpreter .
+    fi
 
 install: true