added check for esp
Merge branch 'master' of https://github.com/ldowson/cs140winter2014
fixed conflict
Merge branch 'master' of https://github.com/ldowson/cs140winter2014
Merge branch 'master' of https://github.com/ldowson/cs140winter2014
Merge branch 'master' of https://github.com/ldowson/cs140winter2014
Merge branch 'master' of https://github.com/ldowson/cs140winter2014
Merge branch 'master' of https://github.com/ldowson/cs140winter2014
added design doc and modified validate pointer