Reorder operations in Dockerfile, to make image creation faster

- Reorder prevents unnecessary building of Boost libraries

Dockerfile

@@ -24,7 +24,6 @@ RUN \
       libtool \
       locales \
       pkg-config \
-      ntp \
       wget \
     && \
     apt-get clean && \
@@ -34,9 +33,6 @@ RUN \
     sed -i -e 's/# en_US.UTF-8 UTF-8/en_US.UTF-8 UTF-8/' /etc/locale.gen && \
     locale-gen
 
-ADD . /peerplays-core
-WORKDIR /peerplays-core
-
 # Compile Boost
 RUN \
     BOOST_ROOT=$HOME/boost_1_67_0 && \
@@ -47,6 +43,9 @@ RUN \
     ./b2 install && \
     cd ..
 
+ADD . /peerplays-core
+WORKDIR /peerplays-core
+
 # Compile Peerplays
 RUN \
     BOOST_ROOT=$HOME/boost_1_67_0 && \