Merge branch 'cleanup-apt' into 'master'

Clean up `apt` configuration and cache

See merge request !21

scripts/install-essentials

@@ -12,10 +12,15 @@ apt-get install -y \
 	logrotate python-docutils pkg-config cmake nodejs \
 	libkrb5-dev postgresql-client mysql-client unzip \
-echo deb http://httpredir.debian.org/debian stretch main > /etc/apt/sources.list
+echo deb http://httpredir.debian.org/debian stretch main > /etc/apt/sources.list.d/stretch.list
 apt-get update -yqqq
 apt-get install -yqq --force-yes git
+rm /etc/apt/sources.list.d/stretch.list
+apt-get update -yqqq
+
+apt-get clean -yqq
+
 # Set UTF-8
 # http://stackoverflow.com/a/3182519/2137281
 LOC=$'LC_ALL=en_US.UTF-8\nLANG=en_US.UTF-8'