repartition: Repartition a 'spark_tbl'
In danzafar/tidyspark: A Tidy Interface to Spark

Repartitions a spark_tbl. Optionally allos for vector of columns to be used for partitioning.

1	repartition(.data, n_partitions, partition_by)

`.data`	a data frame to be repartitioned
`n_partitions`	integer, the target number of partitions
`partition_by`	vector of column names used for partitioning, only supported for Spark 2.0+

## Not run: 
spark_session()
df <- spark_tbl(mtcars)

df %>% n_partitions() # 1

df_repartitioned <- df %>% repartition(5)
df %>% n_partitions() # 5

df_repartitioned <- df %>% repartition(5, c("cyl"))

spark_session_stop()

## End(Not run)