use Ethereum PPA for cryptopp and jsonrpc dependencies

docker/Dockerfile

@@ -7,6 +7,7 @@ RUN apt-get upgrade -y
 # Ethereum dependencies
 RUN apt-get install -qy build-essential g++-4.8 git cmake libboost-all-dev libcurl4-openssl-dev wget
 RUN apt-get install -qy automake unzip libgmp-dev libtool libleveldb-dev yasm libminiupnpc-dev libreadline-dev scons
+RUN apt-get install -qy libjsoncpp-dev libargtable2-dev
 
 # NCurses based GUI (not optional though for a succesful compilation, see https://github.com/ethereum/cpp-ethereum/issues/452 )
 RUN apt-get install -qy libncurses5-dev
@@ -14,15 +15,11 @@ RUN apt-get install -qy libncurses5-dev
 # Qt-based GUI
 # RUN apt-get install -qy qtbase5-dev qt5-default qtdeclarative5-dev libqt5webkit5-dev
 
-# Cryptopp
-RUN git clone --depth=1 https://github.com/mmoss/cryptopp.git
-RUN cd cryptopp && scons --shared --prefix=/usr
-
-# JSONRPC (version 0.2.1, see https://github.com/ethereum/cpp-ethereum/issues/453 )
-RUN apt-get install -qy libjsoncpp-dev libargtable2-dev
-RUN git clone --depth=1 --branch=0.2.1 https://github.com/cinemast/libjson-rpc-cpp.git
-RUN mkdir -p libjson-rpc-cpp/build
-RUN cd libjson-rpc-cpp/build && cmake .. && make && make install
+# Ethereum PPA
+RUN apt-get install -qy software-properties-common
+RUN add-apt-repository ppa:ethereum/ethereum
+RUN apt-get update
+RUN apt-get install -qy libcryptopp-dev libjson-rpc-cpp-dev
 
 # Build Ethereum (HEADLESS)
 RUN git clone --depth=1 https://github.com/ethereum/cpp-ethereum