readme - add link to blog post explaining why checking in dependencies is recommended

Lots of people ask about this and doesn't bother to Google it...
remove unicode space symbol thingy
-offline added
typo fix in --offline
typo fix in --offline
typo fix in --offline
Merge pull request #944 from gergelyke/master

bower's cache added to readme
Add Bower logo to readme
Added config fallback for allow-root check
Merge pull request #976 from hidinginabunker/allowroot_env_conf

Added config fallback for allow-root check