* added singly linked list in java
* added commnets
* addded singly linked list in javascript
* Rename SinglyLinkedLIst.java to singly-linked-list.java
* added singly linked list in c++
* changed .gitignore to ignore binary files for c++ and java
* changed .gitignore to ignore binary files for c++ and java
* i changed as per review , method names in SinglyLinkedList and folder name
* i changed directory name as per convention