Added checkout transaction to CLerk
edited insertBorrowingTuple to take in the respective callNumber and the respective copyNo from the BookCopy table
Merge pull request #12 from g2-aj/branch_alshahna

edited insertBorrowingTuple to take in the respective callNumber and the...
Merge pull request #11 from g2-aj/g3-ks

Added checkout transaction to CLerk
Merge branch 'master' into branch_lin
Finished check book exist function