Made a declaration of Hash method

Haven't got the idea of implementing it.
Initialized backingArray and the destructor

Not sure if they are working.
Deleted Hash declaration and add implementation

Use Hash function implemented in .cpp file and implement find first.
Added declaration of Hash and find implementation

Basically followed the example function in the reading, but not sure if
it works.
Should have followed find method instruction

Not sure if I can return a pointer to that spot.
Implemented add function

Not sure if it would work though.
Debugged find function

And deleted the implementation of add because it was not right.
Debugged find and implemented add

Haven't tested them yet. Hopefully they work fine.
Pointer issue
Debugged the Constructor and add()

Also implemented remove() and keyExists(). But still need to be debugged
Debugged the constructor and add()

Need to implement grow()
Failed to implement grow()

Need to debug the code
Revised keyExists()

Got rid of useless code
Tried to answer some questions
Tried to debug grow() but failed
Debugged grow() and finished all the methods
Revised answers to the exercises

They can still be refined!
Refined answers to the exercises
Merge pull request #35 from YangLi1/master

None