git: add option to select brewed ssl and curl

default (system) install of curl is based on buggy openssl version, added option to choose brewed versions of curl and openssl

there is a lot of issues with git https push - especially when it comes to SNI (SSL Virtual Hosts), choosing brewed openssl and brewed curl that was compiled with brewed openssl, gnutls or polarssl is resolving this issue

all of this added as options, so it does not affect existing or default installs