Solved problem 1.
Solved problem 2.
Solved problem 3.
Solved problem 4.
Solved problem 5. It's almost cheating.
Solved problems 6 and 8.
Solved problem 9.
Solved problems 7 and 10 using the primes package.
Solved problem 12.
Solved problem 13.
Merge branch 'master' of github.com:jimpo/project-euler
Updated README.