Ubiquity UI tests

[Evan Dandrea]

(I've CC'ed ubuntu-installer on this as someone might be interested in
how we came to the decision of what to test)

Per your request, I've come up with the following three initial tests
for ubiquity.  As the partitioner is the most complex and critical
component of the installer, two of the tests focus on it.

* A "next, next, next" install.  That is, selecting the default values
for everything (save the user setup page, where you cannot proceed
without entering a username and password) and insuring that the
install completes without error.
* A install that resizes the old partition to its maximum value and
installs Ubuntu in the remaining space.  This will also uncover any
bugs in our code to set the bounds of the resize bar, and the code to
determine roughly how much space Ubuntu will need.
* A install over top of an existing install that preserves /home.
This can be done by entering the manual partitioner, assigning the
root mountpoint to the existing partition that contains the root
filesystem, and making sure the format box is not checked, then
continuing the install as normal.

Do let me know if any part of this set is problematic, or if you have
any further questions.

Thanks,
Evan