Merge pull request #14 from GEMScienceTools/intoqa

Intoqa
Merge pull request #15 from GEMScienceTools/intoqa

Added missing file
first version of chapter on benchmarks
Merge branch 'master' of github.com:GEMScienceTools/hazard_book_2014
fixed figure dimensions
Added appendix 2 describing OQ-engine benchmark tests
Appendix 2 still with comments