Initialize enabled directory if it doesn't exist

This is to make bash_it work in a new install after
the plugins/enabled directory was ignored
diff --git a/bash_it.sh b/bash_it.sh
index e0cc579..b3cdb73 100644
--- a/bash_it.sh
+++ b/bash_it.sh
@@ -25,6 +25,11 @@
 done
 
 # Plugins
+if [ ! -d "plugins/enabled" ]
+then
+  mkdir "${BASH}/plugins/enabled"
+  ln -s ${BASH}/plugins/available/* "${BASH}/plugins/enabled"
+fi
 PLUGINS="${BASH}/plugins/enabled/*.bash"
 for config_file in $PLUGINS
 do