pypi: Better install_requires parsing:

* Support multi requirements strings (newline separated)
* Ignore comments
* Ignore empty lines
fixes shebang modification when osx_is_app is true
osx_is_app defaults to False
Update CHANGELOG
Add release date for 1.6.0 to CHANGELOG
Fix a Python 3 issue
Update CHANGELOG
Merge pull request #153 from ddale/osx_is_app-fix

fixes shebang modification when osx_is_app is true
Use bash bin/python.app for the python.app shebang line

This is necessary because this sets PYTHONEXECUTABLE correctly.
Merge branch 'master' of github.com:conda/conda-build
fixes a typo in post:fix_shebang
Merge pull request #157 from ddale/fix_shebang_typo

fixes a typo in post:fix_shebang
Merge pull request #156 from userzimmermann/master

Better install_requires parsing for skeleton pypi command.
Update CHANGELOG
Fix GIT_DESCRIBE_*
Merge pull request #159 from sklam/fix_git_describe

Fix GIT_DESCRIBE_*
Show the download bytes in human for in skeleton pypi
Merge branch 'master' of github.com:conda/conda-build
Fix git describe when work directory is empty.
Make it clearer that you install patchelf with conda