Allow specification of page to POST to for HTTP

krb5.conf syntax is now:
`kdc = [(tcp|udp|http)://]<addr.of.kdc>[:<port>][/<page>]`
Add HTTPS transport

Syntax for krb5.conf is now:
`kdc = [(tcp|udp|http|https)://]<kdc.addr>[:<port>][/<page>]`
Update krb5.conf manpage for new kdc syntax