Merge branch 'master' of https://github.com/drshriveer/2013-09-data-structures
fixed error with 'addChild' test
made pass all tests
optimized recursion using booleans
added test for 'add'
added test for 'contains'
added test case for 'remove' item
fixed _.extends() implementation
fixed syntax fault
'contains' works
added 'remove' functionality
added tests for 'insert' and 'retrieve'
added test case for 'remove'
fixed test errors
broken changes from an 'object based' solution to an array based solution
refactored and tried to fix broken issues... returning undefined persist
fixed some logical errors that lead to failing tests
all tests are passing. needs to be refactored
minor refactoring for HashTable using nested arrays
changed white space