merge RUN-cmds for best practice with apt-get in Docker

Former-commit-id: 0efb7cb9b5

Dockerfile

@@ -4,12 +4,9 @@ MAINTAINER Danilo Bargen <mail@dbrgn.ch>
 # Env variables
 ENV DEBIAN_FRONTEND noninteractive
 
-# Install git
-RUN apt-get update \
-    && apt-get install -y git
-
 # Install dependencies
-RUN apt-get install -y --install-recommends \
+RUN apt-get update \
+    && apt-get install -y --install-recommends \
         build-essential cmake g++ gcc gFortran perl git autoconf \
         curl wget \
         unzip \