Feat (docker): add docker aliases (#1147)

Thanks to @malikoth and @saoula for their input.

modules/docker/init.zsh

@@ -0,0 +1,57 @@
+#
+# Defines Docker aliases.
+#
+# Author:
+#   François Vantomme <akarzim@gmail.com>
+#
+
+# Return if requirements are not found.
+if (( ! $+commands[docker] )); then
+  return 1
+fi
+
+#
+# Functions
+#
+
+# Set Docker Machine environment
+function dkme {
+  if (( ! $+commands[docker-machine] )); then
+    return 1
+  fi
+
+  eval $(docker-machine env $1)
+}
+
+# Set Docker Machine default machine
+function dkmd {
+  if (( ! $+commands[docker-machine] )); then
+    return 1
+  fi
+
+  pushd ~/.docker/machine/machines
+
+  if [[ ! -d $1 ]]; then
+    echo "Docker machine '$1' does not exists. Abort."
+    popd
+    return 1
+  fi
+
+  if [[ -L default ]]; then
+    eval $(rm -f default)
+  elif [[ -d default ]]; then
+    echo "A default machine already exists. Abort."
+    popd
+    return 1
+  elif [[ -e default ]]; then
+    echo "A file named 'default' already exists. Abort."
+    popd
+    return 1
+  fi
+
+  eval $(ln -s $1 default)
+  popd
+}
+
+# Source module files.
+source "${0:h}/alias.zsh"