adapt Dockerfile for new project structure

Dockerfile

@@ -1,17 +1,20 @@
 FROM    python:3.6.2
 
-RUN pip install numpy
 RUN apt-get update
-RUN apt-get -y install build-essential  
+RUN apt-get -y install build-essential
+
+# Install TA-lib
 RUN  wget http://prdownloads.sourceforge.net/ta-lib/ta-lib-0.4.0-src.tar.gz
 RUN tar zxvf ta-lib-0.4.0-src.tar.gz
 RUN cd ta-lib && ./configure && make && make install
 ENV LD_LIBRARY_PATH /usr/local/lib
 
-RUN     mkdir -p /freqtrade
+# Prepare environment
+RUN mkdir /freqtrade
+COPY . /freqtrade/
 WORKDIR /freqtrade
 
-ADD     ./requirements.txt /freqtrade/requirements.txt
+# Install dependencies and execute
-RUN     pip install -r requirements.txt
+RUN pip install -r requirements.txt
-ADD     . /freqtrade
+RUN pip install -e .
-CMD     python main.py
+CMD ["freqtrade"]