enhance manpage of ez-ipupdate with explanation of options

Currently options are not explained sufficiently (e.g. after reading the manpage it's not clear what `--request-uri` does).

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: ez-ipupdate 3.0.11b8-13.4.1
Uname: Linux 4.2.3-040203-generic x86_64
NonfreeKernelModules: zfs zunicode zcommon znvpair zavl
ApportVersion: 2.17.2-0ubuntu1.5
Architecture: amd64
Date: Tue Oct 13 09:05:14 2015
InstallationDate: Installed on 2015-04-20 (175 days ago)
InstallationMedia: Ubuntu-Server 14.10 "Utopic Unicorn" - Release amd64 (20141022.2)
ProcEnviron:
 TERM=screen
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: ez-ipupdate
UpgradeStatus: Upgraded to vivid on 2015-04-24 (171 days ago)