update dockerfiles

docker/ubuntu/Dockerfile

@@ -9,17 +9,9 @@ RUN apt-get update && \
 	# add-apt-repository
 	software-properties-common
 
-# rocksdb ppas. then update ppas
-RUN add-apt-repository "deb http://ppa.launchpad.net/giskou/librocksdb/ubuntu trusty main" && \
-	apt-get update && \
-	apt-get install -y --force-yes librocksdb
-
 # install multirust
 RUN curl -sf https://raw.githubusercontent.com/brson/multirust/master/blastoff.sh | sh -s -- --yes
 
-# install nightly and make it default
-RUN multirust update nightly && multirust default nightly
-
 # export rust LIBRARY_PATH
 ENV LIBRARY_PATH /usr/local/lib
 
@@ -29,4 +21,4 @@ ENV RUST_BACKTRACE 1
 # build parity
 RUN git clone https://github.com/ethcore/parity && \
 	cd parity && \
-	cargo install --features rpc
+	cargo install