Update Gemfile
Add test and methods for Exercise 0
Add test and methods for Exercise 1
Add test and methods for Exercise 2
Add test and methods for Exercise 3
Add test and method for max number of an array
Add method and test for puts output of an array (ex5)
Add method and test to add panda to array (ex6)
Add method and test to add string to end of array if string already in array (ex7)
Add method and test to iterate through an array of hashes and print name and occupation (ex8)
Add method and test to determine a leap year (ex9)