Fix permissions issue with data dir

If the mounted data directory on the host is owned by root, the znc user
within the container would fail to write any settings to disk.

Hence this changes ownership of the data directory to the znc user (Uid:
1000) and znc group (Gid: 1000) from within the container.

bootstrap.sh

@@ -6,8 +6,13 @@ set -e
 ZNC_VERSION="1.4"
 
 
-# Install build dependencies.
+# Ensure package list is up to date.
 apt-get update
+
+# Install runtime dependencies.
+apt-get install -y sudo
+
+# Install build dependencies.
 apt-get install -y wget build-essential libssl-dev libperl-dev pkg-config