Merge pull request #2 from unixwars/master

Exercise 1.11
exercise 1-12
exercise 9
Merge github.com:grahaminn/SICP
exercise 9
Merge pull request #3 from trevorstedman/master

exercise 1-12
Exercise 1.8
Merge pull request #4 from GusTheSadGeek/master

Exercise 1.8
ex 10
Added iterative solution
Explanation for excersise 1-14