quieter curl
Merge branch 'master' into feature/quiet-curl
Add documentation for --quiet-curl
--quiet-curl support in zsh completion
--quiet-curl option shown in completion
extract curl handling to separate function
Merge branch 'master' into feature/quiet-curl

Conflicts:
	scripts/functions/requirements/openbsd
bring improved curl handling to installer
remove space from --silent in curl handling
add simplistic __rvm_which to rvm-installer
Merge pull request #1748 from wayneeseguin/feature/quiet-curl

add --quiet-curl, update #1614, update #1745