* Added another function to PerfectCube.java
Added another function to PerfectCube.java and fixed a testing mistake in line number 9
* Created PerfectCubeTest.java
Created PerfectCubeTest.java
* fixed PerfectCubeTest.java
* Fixed bug in PerfectCube.java
Fixed bug in PerfectCube.java in isPerfectCube() function for negative numbers. Now It gives the correct output for perfect negative numbers.
* removed main() in PerfectCube.java