Bug#708551: Updated TODO list

[Mathieu Parent <math.parent@gmail.com>]

- check for "--buildsystem=phppear" and "--with phppear" usage
- check for php5-dev builddep when using PECL
- package2.xml requires a newer pkg-php-tools version (also TODO on this side)
- check for ${phppear:summary} and ${phppear:description} in Description

low priority:
- check for builddep when using roles (currently, only php-horde-role
is shipping a role)

Patches welcome