updated installation and requirements docs
Merge branch 'dev' of https://github.com/OpenMDAO/OpenMDAO-Framework into docs_update
check
cleaning up
cleanup round 2
Merge branch 'dev' of https://github.com/OpenMDAO/OpenMDAO-Framework into docs_update
more details for osx compilers in dev-guide
Merge branch 'dev' of https://github.com/OpenMDAO/OpenMDAO-Framework into docs_update
updated dev_requirements
Merge pull request #1293 from JustinSGray/docs_update

Docs update
Merge branch 'dev' of https://github.com/OpenMDAO/OpenMDAO-Framework.git into realtime
tweaks