fixes ampas#86, build openexr/ilmbase v.2.5 from source

Dockerfile

@@ -9,10 +9,21 @@ ENV DEBIAN_FRONTEND noninteractive
 RUN apt-get -y install cmake
 RUN apt-get -y install g++
 RUN apt-get -y install valgrind
+RUN apt-get -y install git
 
 # install CTL dependencies
-RUN apt-get -y install libilmbase-dev
-RUN apt-get -y install libopenexr-dev
+#RUN apt-get -y install libilmbase-dev
+#RUN apt-get -y install libopenexr-dev
+RUN apt-get -y install zlib1g-dev
+WORKDIR /usr/src/
+RUN git clone /~https://github.com/AcademySoftwareFoundation/openexr.git
+WORKDIR /usr/src/openexr
+RUN git checkout RB-2.5 
+WORKDIR /usr/src/openexr/build
+RUN cmake ..
+RUN make
+RUN make install
+
 RUN apt-get -y install libtiff-dev
 
 # install utilities for convenience, not needed for CTL