updating make instructions for generating src/stan/models/model_header.hpp.d
Merge pull request #97 from stan-dev/feature/fix_model_header_dependency_file

makefile target was incorrect for src/stan/models/model_header.hpp.d
MUse boost::lexical cast for more robust reading of numbers in scientic notation
Removed debug output line
Merge pull request #113 from stan-dev/feature/fix_print_and_sci_note

Fix bin/print and Extremely Small Numbers
stagnant models from bugs volume 2
Merge branch 'develop' of https://github.com/stan-dev/stan into feature/stagnant-model-bugs-vol2