How to transpose dataframe in Spark 1.5 (no pivot operator available)?

I want to transpose following table using spark scala without Pivot function

I am using Spark 1.5.1 and Pivot function does not support in 1.5.1. Please suggest suitable method to transpose following table:

Customer Day   Sales
1        Mon    12
1        Tue    10
1        Thu    15
1        Fri     2
2        Sun    10
2        Wed     5
2        Thu     4
2        Fri     3

Output table :

Customer Sun Mon Tue Wed Thu Fri
   1      0   12  10   0  15  2
   2     10    0   0   5  4   3

Following code is not working as I am using Spark 1.5.1 and pivot function is available from Spark 1.6:

    var Trans = Cust_Sales.groupBy("Customer").Pivot("Day").sum("Sales")