Update gitignore
Update gitignore

Ignore swap files like those from vim.

spark-notebook/spark-notebook,spark-notebook/spark-notebook,maasg/spark-notebook,maasg/spark-notebook,andypetrella/spark-notebook,spark-notebook/spark-notebook,andypetrella/spark-notebook,maasg/spark-notebook,andypetrella/spark-notebook,maasg/spark-notebook,andypetrella/spark-notebook,spark-notebook/spark-notebook