Use CGI::escape rather than URI.escape for query params

[sayhiben]

Explanation:

While SSO worked fine for "normal" email addresses, my usual workflow
involves using the + sign to generate reusable email addresses for
manual testing purposes (e.g., "myemail+0001@gmail.com",
"myemail+0002@gmail.com", etc.).

Because the + symbol represents a space character (" ") within query
parameters, Ambassador's SSO is unable to associate these email
addresses with their respective accounts.

This means users whose email addresses contain the + sign cannot log
into their Ambassador portals via SSO. Ambassador otherwise appears to
support email addresses containing the symbol.

CGI::escape properly converts email addresses to their url encoded form,
but URI.escape leaves them as-is:

CGI::escape('abc+123@gmail.com') => "abc%2B123%40gmail.com"
URI.escape('abc+123@gmail.com') => "abc+123@gmail.com"

See these "fun" links:

• http://stackoverflow.com/a/13059657/983049
• http://stackoverflow.com/questions/1005676/urls-and-plus-signs

[chaselee]

Thanks! Looks good. I'll have a new version up shortly.