singly linked list

"#   (use ""git push"" to publish your local commits)"
"#   (use ""git reset HEAD^1 <file>..."" to unstage)"
"#	modified:   src/main/java/com/anju/collections/List.java"
"#	new file:   src/main/java/com/anju/collections/impl/AbstractList.java"
"#	new file:   src/main/java/com/anju/collections/impl/LinkedList.java"
"#	modified:   src/test/java/com/anju/collections/ListTest.java"