Install ta-lib in Docker with script

works for travis, works for Docker

Dockerfile

@@ -1,19 +1,20 @@
 FROM python:3.7.0-slim-stretch
 
-# Install TA-lib
-RUN apt-get update && apt-get -y install curl build-essential && apt-get clean
-RUN curl -L http://prdownloads.sourceforge.net/ta-lib/ta-lib-0.4.0-src.tar.gz | \
-  tar xzvf - && \
-  cd ta-lib && \
-  sed -i "s|0.00000001|0.000000000000000001 |g" src/ta_func/ta_utility.h && \
-  ./configure && make && make install && \
-  cd .. && rm -rf ta-lib
-ENV LD_LIBRARY_PATH /usr/local/lib
+RUN apt-get update \
+    && apt-get -y install curl build-essential \
+    && apt-get clean \
+    && pip install --upgrade pip
 
 # Prepare environment
 RUN mkdir /freqtrade
 WORKDIR /freqtrade
 
+# Install TA-lib
+COPY build_helpers/* /tmp/
+RUN cd /tmp && /tmp/install_ta-lib.sh && rm -r /tmp/*ta-lib*
+
+ENV LD_LIBRARY_PATH /usr/local/lib
+
 # Install dependencies
 COPY requirements.txt /freqtrade/
 RUN pip install numpy --no-cache-dir \