Have dev use ~/.netrc to store Github authentication instead of juggling raw passwords. [2/4]

[VictorLowther]

This feature migrates us away from doing our own password management
by embedding Github username/password authentication into our curl calls
and remote URL strings. Instead, we add entries for github.com and
api.github.com to the user's .netrc file, fix up all the direct curl
calls we make to ensure they know to look in .netrc for authorization info,
and rely on Git doing the same thing when it has to talk http.

The benefit to doing all this is that we no longer have to worry about
passwords that have special characters in them, nor do we spam auth info
all over the barclamps -- instead, it is in one place that all the tools
know how to access and that is a little more securable.